Sai

is the Anbu Chief of Konohagakure's Yamanaka clan. Prior to this, he was a Root member. As per standard Root training, Sai was conditioned to remove all emotions and as such, had difficulty connecting with others. When he is added to Team Kakashi as a replacement for the rogue Sasuke Uchiha, Sai begins to learn more about people's feelings and tries to develop his personality and identity by forming genuine bonds and rediscovering the emotions he was taught to suppress.

Background
Sai was orphaned as a child and recruited into Root, a secret branch of the Anbu under the leadership of Danzō Shimura. There, he was raised and conditioned to have no personality, personal connections, or a name; "Sai" being given to him for the purposes of joining Team Kakashi. Though largely successful in this regard, Sai retained an interest in art. When Shin, an older Root member, discovered Sai's drawing ability, he encouraged Sai's talent and they became very close.

Over time, Sai came to think of Shin as an older brother and looked up to him. Unfortunately, the final step in Root training called for the two to fight to the death to eradicate all remaining emotions. Before that happened, however, Shin died of an unnamed illness and Sai's Root training suppressed most of the memories he had of him. In the anime, Sai and Shin were forced to fight by Danzō but Shin, knowing that he was dying anyway, told Sai to report to Danzō that he had killed him in battle. Before dying, Shin told his brother that he had to suppress his feelings, and to live for the both of them.

Before Shin's death, Sai created a picture book that would depict all the opponents they faced and illustrate the feelings that they shared for each other. Sai organised the book so that his and Shin's portraits would be located at opposite ends of the book, and in the centre pages would be a picture of them holding hands. Some time after the loss of Shin, Sai forgot that this was his intention, and the picture book was left unfinished, though he could never bring it upon himself to discard the book.

During his time in Root, Sai was ordered to eliminate a large number of individuals that posed a threat against Konoha. At the time he was assigned to Team Kakashi, the last assassination he performed was of Unmo Samidare. In the anime, an attempt to gain a powerful fūinjutsu after seeing the Third Hokage sacrifice his life in an attempt to defeat Orochimaru, led Danzō to supervise Sai while he learned how to use the Sealing Technique: Tiger Vision Staring Bullet, noting that it would be dangerous as he would have to use "emotional energy" in order to make the technique stronger. Sai struggled greatly with this endeavour as it conflicted with his training and, consumed by negative emotions, his training was seemingly left incomplete.

Personality
When first introduced, Sai was distinguished by his total lack of emotion which he often masks with a false, cheerful, yet transparent façade. After much mental conditioning and training while in Root, Sai had suppressed almost all of his emotions, laying all of his loyalty to whoever commands him, and thus making it easier for him to accomplish dangerous, unpleasant, or unethical missions. Due to this training and his lack of social experience and personal initiative, Sai has great trouble in understanding how bonds between people can motivate others. He often showcases this confusion after thinking about why Naruto would go so far to save Sasuke, a traitor, even though Naruto had not been ordered to do so.

Sai's social awkwardness tends to get people angry, because he often speaks without considering his words and their effects on people. This was due to his inability to realise the difference between a rude statement and a true statement. Sai had read somewhere in a book that giving somebody a nickname would bring you closer to that person and develop your friendship, this resulted in Sai hurting Sakura Haruno's feelings, because he called her "ugly", stating the first true character trait that came to his mind. This also nearly led to enraging Chōji, while eating barbecue with Team Asuma and Team Kakashi he nearly called him "fatso" before Naruto covered his mouth before he could finish. Realising he was offending people by saying characteristics that came to his head, Sai decided to take a different approach by saying the opposite of what came into his head. In this way, at the same event, Sai called Ino "gorgeous" (although he truly meant to call her "ugly"), much to Ino's surprise, Naruto's relief, and Sakura's outrage.

After spending more time with Team Kakashi, Sai comes to appreciate bonds, particularly the bond that exists between Naruto Uzumaki and Sasuke Uchiha, though Sai would come to have serious doubts about Sasuke when he began to commit crimes on an international scale, which Naruto would suffer for, leading him to support assassinating Sasuke. This causes him to break out of his emotionless shell and start to remember the times he had with his own "brother", Shin. In doing so, Sai was able to start giving genuine smiles. Wanting to experience personal bonds for himself, Sai sets out to make as many friends as he can. However, since he is learning most of this out of books and by trial and error, he often accidentally ends up offending people with his nicknames and conversation. He has come to develop a more genuine, pleasant, and thoughtful personality, while also showing signs of more emotion, such as enthusiasm and occasional nervousness. In the anime, it was shown from his Infinite Tsukuyomi dream that his greatest desire is to fully rediscover his emotions and connect with as many people as possible through it.

He later appeared to show genuine anger while explaining to Sakura about Naruto's feelings for her and later when she lied to Naruto about the predicament with Sasuke and trying to use a fake confession to get him to give up on Sasuke. The greatest change in his personality, however, came after he encounters his reincarnated brother. When Shin is used as a living bomb by Deidara, Sai became truly enraged for the first time and attacked Sasori and Deidara mercilessly, showing genuine rage on his face. Sai also displayed genuine sadness, shedding tears when his brother was freed from the technique and disappears.

Sai is very observant, and is always focused on his missions. He pays a lot of attention to detail, allowing him to quickly notice if something is not as it appears, as shown from how he easily sees through Yamato's tricks. This awareness spans beyond the trials of duty, as Sai was later quick to understand the nature of Naruto's inner suffering without Naruto even telling him. What he failed to understand, however, was that Naruto was not trying to save Sasuke just for Sakura, something he mentions is due to his still lacklustre understanding of both his Team 7 teammates and emotions in general and he would come to regret when it lead to Sakura's suicidal attempt to stop Sasuke, feeling that as if he was a true friend, he should've found another way that didn't put his teammates at risk. Sai holds Naruto in high regard and tries to assist Naruto whenever he's going through hardships however he can.

This bond with Naruto led Sai to start to understand camaraderie, and by the Fourth Shinobi World War, he realised he understood it as he, Rock Lee, and various others went to assist Naruto as he fought against Tobi. Growing up over the following the years, Sai came to truly understand compassion and love, forming a closer bond with Ino, showing more forwardness in such acts as asking her on a date and holding her hand affectionately. This ultimately led to them forming a family. Through all this, Sai has completely come to reject the teachings of Root, accepting that Danzō's actions, while genuine to protect the village, were misguided and only led to more suffering.

Sai is shown to care greatly for his family, as he has begun training his son in his artistic-ninjutsu, finding humour in Inojin's cruder drawing. Sai also has developed strong parenting skills, being the one who's reprimanding Naruto for not holding back enough when he tried to counter Boruto's shadow clone with his own. His compassion for his son's happiness was also shown from not wanting to hurt any of his friends, regardless of the circumstances. He also believes in a indirect teaching-method, feeling that while people need guidance, they cannot truly grow as people if they don't find the answers themselves.

Appearance
Sai has short, straight black hair, and dark eyes which contrast with his translucent-looking pale skin. He is usually seen carrying a small backpack with his brush, scrolls, and ninja ink in it. He wears a short black-and-grey jacket with red straps — as customary of all Root members, to most likely show his allegiance to the organisation. He also carries a tip-less tantō on his back. The rest of his outfit consisted of a high-collared midriff shirt, black pants, shinobi sandals and gloves with his index and thumb fingers exposed, most likely to facilitate the use of his drawing based techniques. When first seen with Team Kakashi, his jacket has a long right and short left sleeves. He had Danzō's cursed seal on the back of his tongue until Danzō's death, which caused it to disappear. Despite his different hair-style and skin-tone, he is noted by many to physically resembled Sasuke, and ultimately is considered very handsome, as shown from Ino immediate infatuation of him. When he's not on missions, Sai wears a casual outfit consisting of a long-sleeve shirt with a high collar, matching pants, and his regular shinobi sandals. This outfit was first depicted as being purple in colour and later, navy blue. He doesn't wear his forehead protector or gloves with this outfit.

In the anime, when Sai uses the Sealing Technique: Tiger Vision Staring Bullet and his negative emotions surface because of his use of "emotional energy", his eyes turn a translucent red colour and his sclerae turn black. This is apparently, as when Danzō countered the symptoms, ink splattered from Sai's body.

Two years after the Fourth Shinobi World War, Sai grew his hair longer with his bangs framing his face. His attire is similar to his old Root outfit but his jacket is now completely black with both sleeves of his shirt long, and less of his midriff exposed. He also has a large scroll strapped horizontally to his back and his shinobi sandals reach above his calves.

A decade after the Fourth Shinobi World War, his jacket now covers his entire upper body, with both sleeves long. His hair is shorter, and he wears an even larger scroll on his back to perform fūinjutsu. Sai keeps his hair in a short ponytail as customary of the Yamanaka Clan. He has a different styled jacket with the sleeves rolled up and his collar is upturned. The large scroll he carries is attached to his belt and he also wears gloves. He occasionally still uses his forehead protector.

Abilities
As a member of Root, Sai is a highly capable shinobi, who is trained in the organisation's kenjutsu. Being said to be strongest Root member of his generation, Danzō had enough faith in Sai's abilities to task him with single-handedly killing Sasuke. By adulthood, his talents led him to become one of Konohagakure's top authorities as the head of Anbu and regular reporting directly to the Seventh Hokage and aiding him in various decisions.

Ninjutsu
Sai is able to use Earth Release to conceal himself underground without disrupting the surface of the earth. He can also use Fire, Water and Yang Release. In adulthood, since marrying into the Yamanaka clan, Sai appears to have become well-versed (or at least knowledgeable) in their hidden techniques to aid his son's training in them. In the anime, he can also use shadow clones.

Ink Techniques
Sai is able to combine ink with the Body Flicker Technique to create a more effective cover up. However, Sai's most notable talent is his skill as an artist, able to create drawings in mere moments. He uses these artistic skills as a source for his Super Beast Imitating Drawing. Using his custom scroll (which contains a compartment for Sai's ink brush and a supply of ink), and applying chakra into the drawings, his creations come to life.

Sai typically creates giant birds to transport himself or others, lion-like monsters for attack, snakes for restraining enemies, and mice to scout an area. Sai can also create ink clones of himself for reconnaissance. For discreet communiques when he is undercover, Sai is able to turn the words he writes into small animals, allowing them to travel to their intended target unnoticed. He has also demonstrated the ability to create large humanoids that resemble the, which possess enough strength to completely destroy Deidara's clay birds. Sai can also produce explosive tags, as seen when he had multiple birds fly down to bombard his enemies with a chain of explosions.

Fūinjutsu
As noted by Kakashi, Sai is one of Danzō's prized soldiers and as such, his Root training also included learning fūinjutsu. By animating a large tiger from his scroll, he can use it to grab and seal the target in the painting. Due to the preparation time it would take to paint the tiger, he would need allies to protect him while in battle. In the anime, it is stated that Sai uses "emotional energy" to bolster the technique. This is a double-edged sword as Sai becomes susceptible to his negative emotions.

Physical Prowess
Despite not being his speciality, Sai has shown to be proficient in taijutsu. He was able to react and block Naruto's attempt to stab him with a kunai very easily with his tantō. He also was able to subdue Kabuto Yakushi very easily and block Sasuke Uchiha's attempt to stab Naruto, with Sasuke commenting that he blocked the attack in the most appropriate manner. During the Fourth Shinobi World War, he was able to break Shin's neck with a flying knee kick in mid-air. Even without the use of his tantō, he has shown great skill with a bladed weapon and was able to fight equally with an opponent wielding a larger weapon. A distinct advantage he has in battle is to perform techniques with a single hand, leaving the other free for enemy counter-attacks.

Tenchi Bridge Reconnaissance Mission
Sai was assigned to join Team Kakashi by his superior Danzō to assist in meeting with a spy in Orochimaru's ranks to find out about Sasuke Uchiha. Sai was confrontational with his new teammates upon their first meeting, exasperating both Sakura and Naruto. On their way to the rendezvous point, Sai once again aggravated them, questioning Naruto's manhood and insulting Sasuke. The latter caused Sakura Haruno to punch him in anger. As they continued on to the meeting point, Sai questioned why Naruto was loyal to a traitor like Sasuke, to which Naruto stated he was not a traitor, but a friend. Upon reaching the designated meeting place, Yamato went ahead disguised as Sasori so that he could meet the spy. When the spy, Kabuto Yakushi, arrived with Orochimaru to kill Sasori, Sai, Naruto, and Sakura were called in for help.

When Naruto and Orochimaru began fighting, Sai left the rest of the team to begin his real mission. He briefly observed Naruto's fight with Orochimaru, unconcerned with the danger he left Yamato and Sakura in, and approached Orochimaru after he had repelled Naruto with a proposition from Danzō. Orochimaru accepted, and Sai accompanied him and Kabuto back to their hideout. Once arrived at Orochimaru's hideout, Sai was introduced to Sasuke, who had been training under Orochimaru for the past two-and-a-half years. When Sai mentioned that he might get along better with Sasuke than he did Naruto, Sasuke temporally traps Sai within a genjutsu which startles Sai to the ground due to the amount of fear it gave his emotionless self. He was led to his own room afterwards by Kabuto, who locked Sai in upon leaving. Soon afterwards, Team Kakashi tracked Sai down and confronted him about his real mission. Having been caught, Sai explained that he had been assigned to ally with Orochimaru on Danzō's behalf so that the two may join forces in destroying Konohagakure.

Disgusted by the ramifications of this plan, Team Kakashi restrained Sai before setting out to find and retrieve Sasuke. Sai, however, doubted their success, stating that Sasuke no longer cared about them. Naruto, in response, stated that he also used to hate Sasuke, but over time he had formed a bond with Sasuke through their shared experiences, and as such he would do whatever it took to bring Sasuke home. Naruto's dedication to retrieving Sasuke struck a chord with Sai, who was left without words as a result. When Kabuto arrived and freed Sai, Sai instead helped them capturing Kabuto, hoping to accompany Naruto to find out more about bonds. Naruto and Sai split away from Sakura and Yamato to go looking for Sasuke. They were soon found by Orochimaru, and as a result, Naruto distracted him so that Sai could have a chance to scout on ahead. When Orochimaru retreated and Naruto reunited with Sakura and Yamato, Yamato went through the belongings that Sai had left behind. In doing so he discovered Sai's actual mission: to kill Sasuke as a traitor to Konoha.

Team Kakashi raced through the base to find and stop Sai, but Sai had already found Sasuke. Sai, however, truly had a change of heart, and instead, tried to capture Sasuke in order to protect his bond with Naruto. Irritated by Sai's reasons for bothering him, Sasuke attacked Sai, drawing the rest of the team to their location. When they found out what Sai was trying to do, they all teamed up to restrain Sasuke. Although Sai was able to land a successful attack, Sasuke's abilities were too much for them and he prepared to kill them all. He was soon stopped by Orochimaru and Kabuto, who convinced him to spare the team before leaving. Defeated, Team Kakashi returned home. Sai requested that he be allowed to stay as a part of the team and, with Danzō's approval, began to spend time with his new friends. Upon returning to Konoha and failing their mission, Sai began reading about relationships in the hopes of making some for himself.

Twelve Guardian Ninja
In the anime, Team Yamato are sent to help guard anymore tombs of the former Twelve Guardian Ninja from being robbed. Shortly after arriving at the Fire Temple, the team are notified that another tomb has been robbed. The team then set out to find the perpetrators, accompanied by Chiriku and Sora. Along the way they spot caskets moving across a field and onto a cliff where four ninja lied. When they confront the enemy ninja, Fudō traps them in a rocky canyon, which separates everyone. As Sai tries to look for a way out, Fuen halts his attempts each time. He soon figures out that he is being tracked with a chip and plants it on a ink clone. This deceives Fuen, giving Sai the opportunity to sneak attack her from behind with ink lions. Although she is able to counter, Sai is able to escape.

Some time after, Sai stumbles into Sakura, arriving in time to save her from a surprise attack from a giant spider. While he manages to kill it, he gets injured in the process. Sakura tends to his wound, but he is forced to wear an arm brace. After the two meet up with Yamato, they find Naruto being drained of his chakra by Fūka. Before they can do anything, Chiriku and his fellow ninja monks blast the cave open. Deciding that they had stalled enough, the enemy ninja retreat.

When the group returned to the village, Sai was sent to the hospital to be further treated. While Sai was on leave of absence, Sora took his place. Later, Sai sees that the village is being attacked, and sneaks out of the hospital to help Asuma fight Kazuma, enabling Asuma to finish him off.

Akatsuki Suppression Mission
Sai and the rest of team Kakashi were later sent as backup for Team Asuma during their battle with Akatsuki. Because Shikamaru Nara was separated from the rest of the group, Sai and Sakura were sent to his aid, though upon arrival they found that Shikamaru had already defeated his opponent. Sai returned with everyone else to Konoha, having not taken part in the battle. Because Naruto was injured during the battle, he has difficulty eating when they got back. Sai, wanting to ameliorate their friendship, attempted to feed Naruto which angered him since he had wanted Sakura to feed him and Sai had interrupted her doing so. Neither has their way as Kakashi himself took up the task of feeding Naruto instead.

Three-Tails' Appearance
In the anime, Sai was placed on Team One along with Kakashi, Shino and Naruto. His team's duty was to fight any enemies who closed into the area so they wouldn't disrupt the sealing process for Team Three, who were going to seal the Three-Tails. After he had introduced himself to Shino, he found that Shino had a bit of a grudge towards Naruto, since it turned out that though Sai only knew Naruto for a few month and knew more about Naruto, much more than he did. Sai's team ran into Guren and Gozu. As the battle between them commenced, Sai soon took on Gozu alone. Sai managed to temporarily restrain him with his ink snakes but with his brute strength broke free shortly after. The sealing is disrupted and they were forced to retreat and devise another plan.

After he and the other Konoha-nin recuperated, he mistakenly got in between Sakura and Ino's bickering, and by being oblivious to the situation, repeated the names they yelled at each other thus getting himself punched by both of them. He and the others at some point find out that the young boy accompanying the enemies can partially control the beast. They eventually find him unconscious and take him with them. After Yūkimaru was treated by Sakura and Ino, Kakashi decided to use him to conjure up the beast to try sealing once more. After that Sai was tasked with bringing him to a secure place. However, he got attacked by some of Guren's men and despite his efforts, he was defeated and Yūkimaru was captured. Later, he battled foes who were merged but were crushed by the Three-Tails on its ramapage. Having failed to seal the beast again, they returned to their village and left the rest up to the leaf Anbu.

Itachi Pursuit Mission
Along with Team Kurenai, Sai and the rest of Team Kakashi set out to find and capture Itachi Uchiha. When Kakashi summoned his ninken to assist them on the mission, Sai was partnered with Ūhei and Urushi and wondered to himself whether or not he could become friends with dogs.

Fated Battle Between Brothers
He and the other members of the Eight Man Squad were later confronted by Tobi, who stalled them long enough to prevent them from locating neither Sasuke nor Itachi.

Six-Tails Unleashed
In the anime, Sai and the rest of Team Kakashi was assigned a mission involving the Tsuchigumo Clan. When they reached their destination they found the place a wreck and a hurt Tonbee. Sakura healed him and when he regained his strength, he told them that a group of ninja attacked, seeking the Tsuchigumo clan's kinjutsu, and that his granddaughter, Hotaru, escaped through a secret passage with it. Sai, Naruto and Yamato left to find her, leaving Sakura to look after Tonbee. When he, Yamato and Naruto caught up with her, they saw a mysterious guy named Utakata near her. Naruto attacked him under the impression he was an enemy to which it was clarified he was only escorting her until Konoha arrived. Utakata then left Hotaru in their hands, however, she was refused to it and Sai tricked her into letting them escort her to the Tsuchigumo Village. When the group reached the village they left her with the rest of her clan. They returned when they considered the villagers attitude toward Hotaru suspicious, and found she was gone.

Later, Sai and Naruto battled a few Kiri-Anbu because they were attacking Utakata who had Hotaru with him. The leader of the Kiri-nin took Yamato aside to discuss the matters of Utakata. After matters are solved to a certain degree, the groups departed. Sai and the rest soon find out that Hotaru had a scroll that held her clan's kinjutsu embedded in her back, much to the Konoha-nin's surprise.

Some time after, Team Kakashi and Utakata headed to the Tsuchigumo Village again after Hotaru had been kidnapped. While there, Sai, Yamato and Sakura fought the Tsuchigumo clan villagers who were under Shiranami's control and the Magaki Group while Naruto and Utakata went find Hotaru. They departed after Shiranami was defeated and his plan failed.

Pain's Assault
When Naruto entered the Hokage's office, he was seen with Sakura, the toads, Shizune and the Hokage as Naruto learned of his master's demise. During Pain's assault on Konoha, Sai was away with Yamato and Anko Mitarashi, tracking down Kabuto Yakushi. He used a special tracking technique that could not be detected by Kabuto. Anko even congratulated him for that. They stopped the search just after a surprised Yamato had informed the group that Naruto had reached the six-tailed form of the Nine-Tails.

Five Kage Summit
After the invasion, Danzō is made Hokage. He summoned Sai before him and instructed him to keep an eye on Naruto. Sai asked why, so Danzō explained that Naruto, having defeated Pain, was now the village's hero and thus more popular than Danzō himself. However, he was still the village's jinchūriki and therefore must be kept in check. Sai was satisfied with his explanation and went to meet with Naruto and Sakura. The two immediately confronted him about Danzō, asking him to tell them everything he knew. Sai said that he could not, as the cursed seal Danzō had placed on his tongue prevented him from revealing anything about Root. Sakura remarked it was cruel, but Sai explained that it was for the best since Root had done a number of questionable things to protect the village. Sakura refuted his claim, pointing out that Danzō had ordered Sasuke be killed as a traitor. Sai was surprised since Danzō had not told him that during their meeting. They were immediately confronted by Kumogakure ninja who, after their brief skirmish, demand to know what they knew about Sasuke. Naruto, seeing that this upset Sakura, volunteered to tell them all that he knew. Sai secretly watched the meeting and how Naruto could not bring himself to sell out Sasuke.

Naruto allowed Karui to take out her anger on him. Karui happily accepted and proceeded to beat him up, but Sai stepped in once she started to overdo it. When Karui left, Sai brought Naruto to Kakashi and Yamato and then tended to his wounds. Naruto asked that Kakashi and Yamato help him find the Fourth Raikage. When they had agreed, Kakashi told Sai not to tell Danzō what Naruto was doing. After hearing such a request Sai looked rather upset and asked Kakashi if he didn't trust him because he was from Root, but Kakashi answered that he believed in him because he was also a member of Team Kakashi. Hearing these words made Sai happy and drove him to act more resolutely. Sai, after deciding to no longer be just reactive while Naruto is suffering from the current events, later approached Sakura, telling her about what Naruto had gone through with Karui for her benefit. He told Sakura that Naruto loved her, and that trying to make her happy, such as trying to bring Sasuke back to the village, caused him to feel anger, pain and suffering.

Following the Konoha 11's decision to eliminate Sasuke themselves to prevent a war, Sakura asked Sai to help her track down Naruto so that she could speak with him. They found him in the Land of Iron and Sakura confessed her love to Naruto, so now he didn't need to bother fulfilling his promise of retrieving Sasuke. When Naruto didn't believe her, Sakura left with her group. Because she didn't mention the decision to kill Sasuke and that he felt responsible for what she was about to do because of what he had told her back in Konoha, he left an ink clone behind to tell them what Sakura had not. The clone also added that Sakura was likely planning to kill Sasuke personally.

The ink clone helped Kakashi locate Sakura. The real Sai, meanwhile, stopped Sakura from knocking him out and her other escorts, having suspected that she would try to get rid of them so she could fight Sasuke alone. Sakura convinced Kiba and Lee that Sai was a traitor and they started to fight him, but this only made it easier for her to knock out all three. As the ink clone dispersed it warned Kakashi of Sakura's actions. Sai and the others were later woken following the meeting with Sasuke, and as they return to the village they were met by three Root members. They inquired about what had happened. Sai affirmed that the seal disappearing was proof that Danzō had died. He then encouraged them to speak with Kakashi whom he addressed as the "new Hokage" about Root's future.

Power
In the anime, Sai and the rest Team Kakashi were sent to investigate the attack at Tonika Village. Splitting up into two, he goes with Yamato. While on their investigation they run into police from Hachō Village. After hearing an explosion from a distance he and the others go to the location. When arriving he battled Kabuto at first but soon enough a reincarnated Deidara stepped in and his attention was drawn to him. After Kabuto retreated he and Yamato went to gather information on The Hole.

While there, he and Yamato soon battled Deidara and a snake clone of Hidan. Later with assistance from Kakashi and the other Konoha-nin, they discussed Kabuto's possible intentions. After, he joined his comrades in battling Kabuto's reincarnated shinobi. Later, they all returned to Konoha, with Kabuto's plan failed.

Fourth Shinobi World War: Confrontation
When the Fourth Shinobi World War began, Sai was placed in the Surprise Attack Division. He created birds with his Super Beast Imitating Drawing for his Division to head into battle. When they entered the enemy's territory and the rest of the division began making a base camp, Sai took to the air to provide back up in case they were attacked. When he later spotted several explosions near the camp, Sai rushed back, eliminating one enemy as he arrived. Despite having a broken neck, the target got back up, revealing himself to be a reincarnated Shin. Shin apologised to his brother for being forced to fight him, unable to control his own movements because of the technique he was reincarnated with and because he was also being manipulated by Sasori. Sai and Shin traded blows until the rest of ambush team could come to help. Hoheto Hyūga revealed that there was explosive clay stored within Shin. They navigated him into one of Kankurō's puppets before he could detonate, weakening the explosion.

However, the force was still great enough to knock Sai over, causing some of the belongings from his bag to fall out. Shin regenerated from the damage and Deidara promised to use Shin as a human bomb again and again. Enraged, Sai quickly navigated behind Deidara and Sasori and drew two ink warriors that knocked them both into two more of Kankurō's puppets, where they were confined and neutralised. Sai then prepared to fight Shin again, but Shin told him there was no need; Sai had dropped his picture book earlier, and seeing the finished product had unbound his soul, freeing him of the regrets that he had had in life. Tears flowed from Sai's eyes as Shin's body turns to ash and dust.

Sai, Omoi, and Zaji were sent out to find other Akatsuki cells. When they came across a group consisting of Haku, Zabuza, Gari, and Pakura, Sai created several ink birds with explosive tags attached to bombard them with. Although the revived ninja recovered from their injuries, Sai continued the assault until backup could arrive. Haku managed to destroy the birds they were riding on, causing them to fall to the ground. Before they could be killed, fortunately, the Third Division arrived to help. They later joined the division in protecting Kakashi as he executed his strategy. After Zabuza and Haku had been dealt with, Kakashi asked that Sai back him up with the sealing techniques he had learned from Root. Sai was reluctant, but Kakashi insisted that, as one of Danzō's most prized soldiers, Sai needn't hold his emotions. Later, Sai was seen among the rest of the Third Division as they recuperated after the first day of war.

Fourth Shinobi World War: Climax
The next morning, Sai alongside the Third Division restarted their assault on the Seven Ninja Swordsmen of the Mist. Drawing a gigantic tiger, Sai launched his Sealing Technique: Tiger Vision Staring Bullet at Fuguki Suikazan who had been incapacitated by Kakashi. As the tiger dragged Fuguki back into the drawing, a noticeably winded Sai told them that he could still go on. Lee told Sai to just concentrate on sealing the enemies, he would protect him while Sai's at it. As a new wave of White Zetsu Army clones approached, Sai looked on as Naruto's shadow clone arrived on the battlefield to confront them. In the anime, Sai also used this technique to seal away Jinin Akebino, and a number of other reincarnated shinobi as well. After being informed by Inoichi from HQ that Naruto and B were fighting the "masked Madara", Sai and the Konoha 11 rushed to his aid. As he ran, he stated that if it were not raining, he could use his Super Beast Imitating Drawing technique to get to Naruto faster. After Lee had, however, spurred him on, Sai thought to himself that he finally and completely understood what it meant to have friends.

Upon arriving at the battlefield, he apologised to Kakashi for their late arrival and later stood alongside the remaining members of the Allied Shinobi Forces to face their opposition. When B had regained enough chakra, Sai flew him towards the Ten-Tails atop one of his birds, allowing B to get close enough to launch a counter measure against the beast.

Later as the Ten-Tails matured and the Alliance launched a counter assault, Sai attempted to attack the Ten-Tails' body from above, avoiding its copies, but was soon spotted and knocked out of the sky. After being saved by Naruto, Sai concluded the only way to reach the beast was to take out the larger enemies first and slither past, but that would require a method to get into range quickly and once they were there they would be without healers. His teammates of Team Kakashi responded by summoning a snake, a toad, and a slug respectively.

While the Allied Shinobi Forces and the deceased Hokage marvelled at the original Team 7's combined performance, Sai questioned Jūgo about Sasuke's true motives, to which he replied that even he himself didn't know. He would later tell Sakura that since he didn't know Sasuke much he could observe him without friendly feelings involved and that he couldn't trust him. He proceeded to question Sakura how she truly felt about Sasuke, to which she replied that she was happy Sasuke had returned and that they could trust him. Sai then thought that sincere as her words sounded, her smile was fake.

Birth of the Ten-Tails' Jinchūriki
After the Ten-Tails transforms into its true, tree-like form, it ravaged the Alliance in an attempt to consume their chakra. Sai, seemingly having avoided the assault, crouched and tended to a wounded Sakura. Thankful that Sakura was all right, their attention is soon drawn to Shikamaru's predicament. When Katsuyu noted that it would not be able to remotely assist him because its clones had been killed as well, Sai and Sakura rushed to Shikamaru's side to help their fallen comrade. Responding when Naruto called for them telepathically, Sai the Konoha 11 shinobi are shocked when Naruto's Tailed Beast Mode mantle forms around them as well when he enters one of Kurama's tails. His directives clear, Sai and the others used the Rasengan, which Naruto had formed to break down Obito's defence and give Sasuke and Naruto a clear shot at attacking their opponent. He and his comrades later also aided Naruto in wresting control of the tailed beasts' chakra from Obito in order to stop the Ten-Tails' tree form from blooming. Ultimately, they succeed in removing the tailed beasts from Obito, reverting the Uchiha to his original form. Sai then joins the others in aiding Hashirama against Madara.

After Hashirama is able to subdue the Uchiha, Sai moves in to seal him for good. Moments before the seal is complete, Madara has Black Zetsu merge with Obito, forcing him to revive Madara, granting Madara full access to his newfound might and break free of both Sai's seal and Hashirama's restraints. After being revived and gaining access to his full power, though without his dōjutsu, Madara was easily able to overwhelm the shinobi in the surrounding area, including Sai, before absorbing Hashirama's senjutsu chakra and going to capture the nine tailed beasts. Sai then teamed up with Sasuke, letting the Uchiha perform a sneak attack from the air through the use of a ink bird.

Much later, after Madara became the Ten-Tails' jinchūriki and reclaimed his missing eye, Sai stood next to Hashirama while the Infinite Tsukuyomi was cast, before falling prey to it like the rest of the world and being captured by the roots of the Ten-Tails. In the anime, he dreamed of perfecting his natural smile and expressing himself, to which he made friends with everyone who loved his smile.

Kaguya Ōtsutsuki Strikes
Ultimately, Sai was freed from the genjutsu by Naruto and Sasuke as the war finally ended.

Kakashi Hiden: Lightning in the Icy Sky
Nearly a year after the end of the Fourth Shinobi World War, Sai and Naruto are on a mission in the Land of Waves to capture Garyō, leader of the Ryūha Armament Alliance, a group that follow the example that they believe was set by Madara Uchiha, and in doing so has cost the lives of several of the Land of Waves' citizens. While dealing easily with most of the enemy forces, Garyō's bodyguard holds them off using Ice Release. Garyō insists that his group is doing the world some good by releasing it from the corruptive influence of money. Ultimately, Sai and Naruto capture Garyō on and leave on Sai's bird.

Two months later, when the Tobishachimaru, an airborne ship, is commandeered by Garyō's men in an attempt to free him from the Hōzuki Castle, Sai is sent to aid Kakashi in the air. Sai arrives in to save Kakashi and Guy as they begin falling from the sky. Kakashi informs Sai of what they learned about the Armament Alliance's shinobi and asks how things are going on Konoha's end. Kakashi sends a message to Ino that Tobishachimaru is heading to Blood Prison and asks Sai to take him back to the ship so he can try and stop it. Sai complies, but finds the Tobishachimaru has risen well above its usual altitude owing to the ongoing conflict on board. After getting Kakashi back inside, the hijackers agree to let Sai take a young boy with asthma off the ship but is warned they will kill a hostage if they see him again.

Shikamaru Hiden: A Cloud Drifting in Silent Darkness
During an investigation about the missing shinobi in the land of silence, Sai sends a message using his super beast imitating drawing to Kakashi in which Sai warns of the threat of Gengo and how he is unsure of his own beliefs of the current Shinobi Union.

During Gengo’s speech, Shikamaru attempts to assassinate him but is intercepted by Sai, who is now under the influence of Gengo's genjutsu. They battle until Shikamaru is ultimately captured and imprisoned. Later Temari comes to Shikamaru’s aid but is then forced into battle with Sai. Sai is able to pierce through Temari's fan and stabs her. Before he is able to deal the finishing blow, Sakura knocks him away and Chōji then restrains him.

Ino, after having read his distressed letter is desperate to rescue him from his inner conflict and performs her Mind Body Switch Technique on him as she delves into his mind. Despite the danger for herself she dives deeply into Sai's heart as she feels she is the only one who can rescue him. She feels that she wants to learn more about him and his loneliness as she dives deeper down into him. Ino finds him trapped deep in his consciousness, crying and wrapping himself with the memories of his friends and she calls out to him before putting a reassuring hand on his shoulder which he returns with a heartfelt smile. After the two wake from Ino’s jutsu, they both instinctively reach out for each others hands and Sai thanks Ino as her eyes begin to tear up before affectionately calling her "Miss Beautiful". After they defeat Gengo, Shikamaru checks in on an ashamed Sai and assures him that he is not to blame for anything he did while under Gengo's control before asking Ino to look after Sai.

The Last: Naruto the Movie
Two years after the Fourth Shinobi World War, Sai was drawing a scenery outside of Konohagakure in the middle of the night, only to notice the moon's descent towards the Earth and a hooded shinobi riding on a flying creature while carrying the unconscious Hanabi Hyūga, much to his shock. He tried to chase after them, only to be taken down before he could rescue Hanabi. After reporting to the Sixth Hokage about Hanabi being kidnapped by Toneri Ōtsutsuki, he joins with Naruto, Sakura, Shikamaru, and Hinata on a mission to rescue her.

The team travel by Sai's ink creations where Hinata remarks on seeing a glowing underground spring. Upon reach the spring, Sai informs them that the river does not make them wet, making it easier to travel through. Entering the river, the team fell under a genjutsu, with Sai dreaming about his happy experiences with his brother until Sakura released them from the genjutsu. Further advancing through the spring, Sai, Shikamaru, and Sakura notice Naruto and Hinata were left behind but before they can decide anything, they are attacked by the Moon entrance's Gatekeeper. With their combined efforts, they managed to defeat it with Sakura striking it along with its inner organs.

After Naruto is brought out of his depression by Sakura, she and Sai go to save Hanabi while Naruto and Shikamaru go after Hinata. After Toneri's defeat, the group heads back for Konoha. Later, as Naruto began dating Hinata, he borrowed one of Sai's instruction books about relationships, particularly about dating protocol.

Sakura Hiden: Thoughts of Love, Riding Upon a Spring Breeze
Kakashi meets with Sai and tells him about two separate attacks by unknown perpetrators against the Fire daimyō and Homura Mitokado. Although nobody was badly hurt and there's no proof the two attacks are connected, Kakashi wants Sai to investigate both incidents by himself.

Sai meets with an informant just outside of Konoha and sends him to investigate if some criminals listed in the Bingo Book are behind the two attacks. As he returns to the village, Sai is attacked by two masked individuals. Although each of the attackers has a cloak of tailed beast chakra, he is able to drive one of them off and capture the other. Sai starts questioning the captive, but when the man begins to respond a juinjutsu activates and his body blows up. Sai reports this to Kakashi. Both observe that the attacker's suicidal juinjutsu is similar to what Danzō Shimura used on his agents. This, combined with the fact that nobody but an Anbu could have even guessed Sai's assignment and thus known to attack him, convinces Kakashi that it is all part of a scheme concocted by Kido Tsumiki, a former ally to Danzō. Kakashi instructs Sai to focus his investigation on Kido.

Sai follows Kido's movements between his different hideouts for three days, but he has no way of getting inside any of them without revealing his presence. His informant requests a meeting and, there, reports a rumour about Sasuke: that he approached some arms dealers several weeks earlier seeking weapons for an attack on Konoha, and then killed the dealers when they failed to cooperate. He also reveals that, after the war, he saw Anbu collecting samples from the Valley of the End and the bridge where Sasuke fought Danzō. Sai pays him for this information and requests another meeting in the future.

When it becomes clear that Sai's investigation into Kido is the same as Sakura and Ino's investigation into an impostor of Sasuke, Kakashi merges their investigations. Ino dubs themselves Ino–Saku–Sai and they promise to keep each other informed of their findings. Shortly afterwards, Ino visits Sai at his home to inform him that Sakura has been captured by Kido. Sai and Ino go to one of Kido's hideouts and Ino senses the interior for Sakura's chakra. She isn't there, but Sai decides they should see what intel they can get anyway. Ino uses the Mind Body Switch Technique on the hideout's sentry while Sai captures them, her first time using such a tactic without Shikamaru and Chōji. When the sentry, an acquaintance of Sai's, is unwilling to answer their questions, Sai forces Sakura's whereabouts from him by tickling him with a paintbrush. They go to the hideout where Sakura is being kept on Sai's imitating bird. When they arrive they find that Sakura has already escaped and is on the offensive.

Sakura, Sai, and Ino work well together despite being outnumbered. They defeat all their opponents but Kido and Magire. Since Magire is a medic-nin, they decide to separate Kido from him so that Magire can't heal his injuries. Sai and Ino exchange attacks with Magire, but neither side is able to hit the other. Magire activates a synthetic tailed beast cloak and, with its tails, is able to create glowing orbs that detonate on contact. While Sai tries and fails to overpower Magire with his Super Beast Imitating Drawings, Ino takes control of an eagle which she uses to stab Magire from behind with a poisoned kunai. Magire's movements slowed, allowing Sai to deliver a finishing blow. Kakashi arrives to help soon after Magire is defeated, with Naruto and Hinata accompanying him. Together, they head into the forest to help Sakura. However, she defeat Kido with her Cherry Blossom Impact. Their mission completed, Ino–Saku–Sai disbands.

Konoha Hiden: The Perfect Day for a Wedding
Sai attended Naruto and Hinata's wedding alongside Ino, where he was seen holding Ino's hand, showing they were in a relationship at the time. They were described as looking blissfully happy as their friends teased them on the progress of their relationship.

Sasuke Shinden: Book of Sunrise
Sai along with Naruto and Sakura attend a meeting with Kakashi where he informs him that Sasuke has successfully received the message regarding missing ninjas and asking him to investigate. During this, Konoha is invaded and Sai transports Naruto and Sakura to the scene using his Super Beast Imitating Drawing where they are joined by Ino, Shikamaru and Chōji. Ino recognises one of the invaders as a patron of her family's flower shop known as Tadaichi and they suspect the invaders are under the influence of a genjutsu. Hinata and Aoba join their efforts in successfully stopping the invaders however both Ino and Aoba pass out from using their techniques and Sai transports the two to the hospital as Sakura provides aid.

Shikamaru and Chōji decide to visit Ino at the hospital and find that Sai is watching over her whilst she sleeps as he sketches a flower that Ino's mother brought her. They discuss the attack from a few days earlier and the heightened security measures that have since been put into place. They begin discussing possible motives, but then realise they shouldn't be doing this while Ino is recovering. Shikamaru and Chōji get up to leave, but Sai remains, claiming that he will leave as soon as he has completed his drawing, however Shikamaru notices several of Sai's already near-completed sketches in the trash as he exits. Shikamaru and Chōji realise that Sai did not want to leave Ino's side and begin discussing how much he has changed from the emotionless man they first met.

New Era
Sai eventually married Ino and took on the Yamanaka name. At some point, he became the director of Konoha's Anbu. In the anime, he would also work part-time at Yamanaka Flowers with his wife. They have a son together named Inojin, whom Sai helps train to become part of the new generation Ino–Shika–Chō alongside his wife.

Academy Entrance Arc
In the anime, as mysterious attacks began happening more commonly and expanding in area, Sai was called to help in the investigation. He later found evidence to suggest that the real goal of the perpetrator was to harvest people's chakra. It was also discovered that the Wood Release was possibly involved. As Root had a history of conducting its own secret research on the famed power of the First Hokage, Sai went to research more of the disbanded Anbu unit alongside Shikamaru. As the attacks continued to occur, Sai intensified his efforts. While Naruto told him to calm down, Sai was determined to save the potential culprit from following the misguided ideology of Root.

Later, a strange release of chakra began spreading throughout the village. As it showed a similar nature to the chakra of the rampages, Sai went to act. His investigation led to an old facility of Root, which turned out to be the hideout of the late-Tanuki Shigaraki, one of Danzō's top researchers and most loyal followers. Putting the pieces together, Sai remembered that Tanuki was in charge of creating an ultimate weapon made from the First Hokage's cells. While looking around the demolished building, he found a picture of Tanuki, with a young girl Sai immediately recognised as Sumire Kakei. After reporting his findings to Naruto, Sai and his unit went in search of Sumire, who disappeared from the hospital. Sai soon found her and subdued her. While preparing to take her in, she unleashed the Nue. The rampaging beast gave Sumire the chance to escape while Sai and his unit attempted to hold off the beast. Kakashi soon appeared, severing its tail, only for the creature to sprout dozens of smaller tails and steal people's chakra. As Kakashi organised the unit to hold off the creature, it suddenly teleported away.

Kakashi deduced that the creature acts differently from normal summonings, naturally existing in its own separate dimension. By morning, Sumire returned from the separate dimension along with Boruto and Mitsuki. Sai, still sympathising with Sumire's history with Root, offered to help her forge a new brighter path. Having let got of her anger at the village thanks to Boruto's words, Sumire accepted Sai's offer and peacefully turned herself in. Sai promised Boruto that she would be fine. Later, Sai discussed the future of Sumire with Naruto and Shikamaru. Sai also removed Sumire's Academy records to weigh in their options.

Sarada Uchiha Arc
On the day of the Five Kage Summit in Konoha, Ino becomes irritated that her son Inojin didn't turn up to his training, as Sai attempts to calm her down.

The week before Inojin's Academy graduation exam, Sai practices his signature technique with his son. When Naruto and Boruto Uzumaki sparing session interrupts them, Sai tells the Seventh it's petty of him to consider using multiple Shadow Clones against Boruto. Afterwards, Inojin tells him his taste in art is ancient.

Naruto Shinden: Parent and Child Day
When Konohagakure started a new annual holiday, Parent and Child Day, Sai spent it with his son. They were also accompanied by Shikamaru, Lee, and their respective sons. Later, he and Inojin entered an eating competition, which ultimately left them sick from overeating and disqualified. In their home, at the end of Parent and Child Day Sai rests in Ino's lap as she affectionately comforts him.

Graduation Exams Arc
The morning before training, Sai discovers that Inojin has been photocopying his Super Beast Imitating Drawing instead of drawing by hand due to finding it exhausting much to Sai's shock. However, during their training, Inojin loses the ability to perform the technique even after drawing by hand. Inojin then asks his father for the reason he can no longer perform their technique, instead Sai advises his son to enter a children's art competition to figure out the answer himself much to Inojin’s displeasure. After Inojin loses to Himawari Uzumaki, Sai attempts to guide him by telling him to find the difference between himself and Himawari. However, this only leads to Inojins frustrations building as he continues to fail in performing the technique which then causes him to attempt to learn and use his mother's Mind Body Switch Technique instead.

Whilst working together in their flower shop, Sai tells Ino of his belief that their son needs to find the solution to his problem on his own for his own benefit or else it would have no meaning but Ino remains worried that Inojin may give up altogether. Sai then affectionately comforts her by telling her that he has faith Inojin will succeed because he is their son, causing Ino to become flustered. Sai tells Ino that he loves art as it brings him closer to people and he believes Inojin needs to rediscover his own passion for art. Ino then tells him he should express his feelings regarding art more to their son as it may help Inojin but Sai says he doesn't quite know how to, causing Ino to show amusement on how awkward her husband can sometimes still be with expressing himself.

Whilst Inojin prepares to throw away his old drawings, Ino and Inojin discover one of his old drawings he made of his family as a child and Ino remarks how happy Sai was when he saw it which motivates Inojin to ask Himawari for help to learn about art.

After Inojin has learnt the true emotional meaning of art and is able to perform the Super Beast Imitating drawings once again, he returns to the Yamanaka flower store where Sai and Ino are working and they share a heartfelt family moment when Sai reveals he always keeps his favourite drawing Inojin made as a child of their family in his jacket and tells his son how he will always believe he can overcome any obstacle.

Byakuya Gang Arc
Later, when a group of self-proclaimed noble thieves began making various heists throughout Konohagakure, their act of distributing their stolen wealth to the poor began gaining much support from many of the villagers. Even more, swarms of protesters began emerging in the village against various legitimate companies, fuelled by the Byakuya Gang's claims of the said companies being corrupt, one of which included the Kaminarimon Company. In hopes of better understanding this new enemy, it was decided to talk to the other villages for any information on the Byakuya Gang.

Later, the villagers supporting the Byakuya Gang began acting out against companies accused of corrupt actions. Sai joined his fellow ninja in working to pacify the situation. Ultimately, it was discovered that several of the protestors were under genjutsu. Sai helped in dispelling the genjutsu. This along with Naruto's speech was able to peacefully end the riots.

Versus Momoshiki Arc
As the next Chūnin Exams drew nearer, Sai continued to watch over Sumire's development. He would regularly make contact with her jōnin-sensei Hanabi Hyūga, advising her to let Sumire go at her own pace for reconciling with her friends.

Later, Sai is put in charge as the proctor of the first phase of the Chūnin Exams with Shikamaru Nara. For the test, Sai asked the participating genin teams to answer a true or false question on a novel series about ninja strategies. To everyone's surprise, Sai revealed neither answer was correct and all the teams were sent hurling into a lake of ink; those who didn't "turn black" passed. Sai explains that the purpose of the test was to test everyone's reaction in a critical situation, and his son, Inojin, comments to his team that only his father could come up with such an idea.

Mitsuki's Disappearance Arc
In the anime, when two chūnin gate guards were attacked by unknown assailants, the village was put on lockdown. Sai oversaw the investigation of the attack, finding Mitsuki's forehead protector. Sai then reported to Naruto and joined him when overseeing Ino probe one of the guard's mind for answers, learning that Mitsuki had left willingly with the attackers. When Naruto revealed to the others Mitsuki was in fact Orochimaru's son, much outrage followed from learning that Naruto would permit an offspring of the man who killed the Third Hokage live in Konohagakure, let alone keep it a secret. Naruto rationalised this on the grounds that Orochimaru's conduct as changed from before and that his aid in investigating the Ōtsutsuki. Despite this, noting the unpredictable nature of Orochimaru, the meeting ended with deeming the Oto-born boy as a threat.

Later, as talks about what to do about Mitsuki's apparent betrayal continued, it was reluctantly determined that they would have to place extreme punishment for Mitsuki. Overhearing this, Konohamaru insisted that he would be the one to bring Mitsuki back, which Naruto reluctantly agreed to.

After finally getting approval from the five daimyō, Naruto and an escort moved out to deal with the danger in Iwagakure, leaving Shikamaru in-charge during the Hokage's absence. Before leaving, they were confronted by Team 7's fellow genin. Having learned of their friends danger, they were determined to help and requested to join the Hokage. While Naruto initially refused to put the genin in danger, the group firmly said they will go with or without his approval. Admiring their loyalty to their friends, Naruto decided to let them, impressing Sai.

Ultimately, the Fabrications were defeated by the combined effort of Konohamaru's students and Ōnoki, who passed away from the effort. Upon returning to Konohagakure, Sai and Konohamaru debriefed Mitsuki on his actions. Ultimately, accepting Mitsuki's actions as not treacherous and beneficial to Iwagakure, it was decided to pardon him, but with the punishment of revoking his shinobi status. Later, due to Kurotsuchi's gratitude and recommendation, Team 7's genin had their respective shinobi statuses reinstated.

Some time later, Sai was officially made the sensei and squad captain to Team 25.

One-Tail Escort Arc
In the anime, after returning from a vacation, Sai was sent on a mission to Sunagakure to investigate Sasuke's sudden disappearance. Along the way, he stumbled upon Shinki being interrogated by Mirai Sarutobi for unsanctioned entering of the Land of Fire. Acknowledging Sai as an above-chūnin shinobi, Shinki revealed his mission from Gaara to deliver the sealed Shukaku to mission and alert Naruto about the location of Urashiki Ōtsutsuki, where he was currently attacking Boruto as a decoy. Sai ordered his men to alert the border security about Urashiki while Mirai and Shinki would remain on standby and he delivered Shukaku to Naruto.

Time Slip Arc
In the anime, Inojin approached his parents with a desire to master the Mind Body Switch Technique, believing he needed to become stronger. After showing ease with performing the technique on small animals, Ino had Inojin attempt to perform the technique on Chōchō to prevent her from reaching a bag of potato chips. He was unable to overcome her will, causing Ino to become frustrated at him for wanting to give up. Sai attempted to intervene, only to lead to a quarrel between them over Inojin and his training. Inojin tried to perform the technique on both of his parents, to no avail. About to give up, he performed the technique once again into his mother and revealed to her that Sai told him how she had once saved him with the Mind Body Switch Technique and now his goal is to help others using the jutsu, thus leading him to gaining control of Ino's body. Sai embraced Ino with a hug and they complimented Inojin for having mastered the technique before walking back to home together.

Mujina Bandits Arc
After the Ōtsutsuki attack on the Chūnin Exams, Sai and Ibiki Morino report that Katasuke Tōno was under mind-control of a third party to Naruto, and suggest it's likely that the perpetrator was after Konoha's technology. Afterwards, Naruto has them look further into the matter.

In the anime, Sai was part of the briefing of Team 7's mission to infiltrate Hōzuki Castle to verify the information about the Mujina Bandits offered by Kokuri in exchange for protection. After losing contact from Mujō, the prison warden who was working with Konohagakure, Naruto sent Sai and a team to investigate. Upon arriving, they learned that Team 7 had attempted to escape the prison after Benga began abusing his newfound power. After Benga's death and Mujō's recovery, they learned that Kokuri's sentence ended a while ago, but had been extended by Benga. Sai discussed the report of the Mujina Bandits with "Kokuri" before letting the man go free.

Several months later, Sai was tasked with escorted Ikkyū Madoka, the Fire daimyō, to meet with Naruto. In the anime, he learned Ikkyū was gathering a large amount of money, Sai and his genin team went to meet with the daimyō. There, he learned that Tentō Madoka was kidnapped. Before Sai could act, they learned that the Mujina Bandits' leader Shojoji was captured and Tentō was saved by Team 7. Sai and Ibiki were tasked with interrogating the leader, Shojoji. While arrogant at first and demanding compensation, the timely arrival of Sasuke and his dark reputation quickly swayed Shojoji to talk. While knowing very little, Shojoji explained that mark on Boruto's right palm was identical to one used by an organisation called "Kara". He also said that the marks' nature is vaguely similar to Orochimaru's Juinjutsu.

Kara Actuation Arc
In the anime, after Sasuke finished probing Shojoji's mind, he learned that Kara was apparently last seen hidden in Amegakure. Sai and his team was assigned to aid Sasuke in investigating this new shadow organisation. There, Sai was shocked to see how much the village had decayed since the last great war. His team found a series of underground tunnels that were sealed off due to a gas leak and mapped it out. Sai ordered the genin to return to the village, deeming the rest of the mission too dangerous for them while he went along with Sasuke. As they entered the area, there were assaulted by Garashi Tōno, an orphaned citizen of Amegakure. He insisted that they were enemies who killed his friends. Sai however quickly subdued him and explained their situation. Calming down, Garashi explained how a group of people were conducting an experiment underground. When he and his friends went to spy on the strangers, they were spotted and gas was set off to kill them. Garashi agreed to take them through the tunnels. This however turned out to be a trap, as Garashi ensnared the Konoha-nin and gassed them, revealing him to be a supporter of Kara after the struggles he had to endure since the Fourth Shinobi World War. Sai and Sasuke saw through his deception and used shadow clones to bait him. Before they could get information from him, Garashi was tricked also by Kara, as his gas mask was tampered with and he succumbed to the poison gas. As the tunnels began to collapse from another trap, they learned that Kara had been stationed there and was performing biological experiments. Sai and Sasuke reported their findings to Konohagakure.

Later, Konoha learned that Victor, president of the Land of Valleys' premiere medical and research company, was in fact a member of Kara. Sai reported neither Victor nor Deepa were listed among any villages' Bingo Books. Later, after their defeat, Sai headed up an investigation on Victor's company, learning that nearly all the workers were oblivious to Victor's true goals. He also found scriptures relating to Shojoji's intel, and vague information of a "vessel". A meeting was held to discuss the next action against Kara, knowing that they had spies everywhere. Konoha leadership considered closing off the gates to Konohagakure to stop the flow of information. Ultimately, Naruto decided to not close the gates as it would deter cooperation with the outside world, instead deciding to reinforce security, putting Sai in charge of it.

Later, Sai took the role of a mock intruder when Ino organised a trial run of the village's new sensing security system. When Inojin failed to apprehend a single mock intruder, he told his father he thought Ino was disappointed in him. He explained to Inojin that Ino's dedication to sensing stems from her admiration for her father, who died during the war. She was inspired by him, and avoided forcing Inojin to take on sensing because she wanted him to be inspired by her as well.

Ao Arc
In the anime, Sai attended the memorial service for the fallen people of the Fourth Shinobi World War.

Later, when Naruto decided to test Katasuke's new Scientific Ninja Weapon, Sai and Shikamaru watch Naruto test it against Boruto at the Training Hall. During the match, Sai comments how Boruto attacking his father from behind is a ballsy move. In the anime, when Konohamaru and Mugino went missing while on mission to investigate a state-of-the-art crashed blimp, Sai found it very concerning. They wondered if Kara was involved.

Kawaki Arc
When Team 7's mission discovered a mysterious boy named Kawaki who was connected to Kara, it was decided to keep him in Konohagakure under Naruto's care. In the anime, he was detained at the Advanced Technology Research Institute in Ryūtan City, prompting Sai and Naruto to go immediately and meet the boy. On the train ride, Sai and Naruto discussed the situation with Kawaki. Sai noted that it was risky to take such a mysterious boy back to the village. Naruto understood Sai's fear, knowing that Kara's desire of the boy could lead to the village becoming a battlefield again. Upon arriving in the station, they learned that Kawaki escaped and was on a rampage. Before Naruto and Sai could act, they met with Boruto and Sumire, the latter insisted to not hurt Kawaki. She noted that Kawaki's rampage stemmed from emotional scars due to his troubled past.

Later, in the anime after Delta of Kara attacked the village and failed to retrieve Kawaki from Naruto, a discussion was brought up about keeping the boy in the village. Sai thought it was best to keep Kawaki in the most secure area, the village, to impede Kara's plans. Later, Sai sent out a note to Sasuke, assigning him another mission that required Sasuke's specific abilities.

As Kawaki began opening up to people, Naruto decided to teach him ninjutsu at his request. During training, Sai and Shikamaru discussed whether or not they could really trust Kawaki. Sai felt they didn't have enough information to make any conclusion. He also informed Shikamaru they were able to recover coordinates from the intel retrieved by Konohamaru, and despite believing it was a possible trap, he passed it along for Sasuke to investigate, as space–time ninjutsu was required. Later when Inojin and Shikadai discussed Kawaki's trustworthiness, Inojin noted that Sai seemed to trust Kawaki on a personal front. Later, after the village was infiltrated and attacked by Jigen, using Kawaki's Kāma as a portal to get in, the village was put on high alert. In the anime, as Naruto and Sasuke were recovering from a near-death experience against the leader of Kara, they discussed recent developments. Sai and Shikamaru were concerned to learn that Kara had a Ten-Tails. When Sasuke mentioned he could no longer access the Ten-Tails' pen, Sai suggested they had changed the dimension's coordinates.

In the anime, Sai and Konohamaru were assigned a mission to investigate Boro's cult in an attempt to learn Kara's Ten-Tails' new whereabouts. Claiming to wanting to join the cult, the two learned that some cultists would sometimes disappear. Tricking one of the cultists into trying to contact Boro, they uncovered evidence the missing cultists had died in Kara's Vessel experiments. Despite exposing Boro's role in the plagues that caused many of the cultists to join, and in the death of the missing cultists, many remained loyal to him. Delta arrived to destroy the facility, which shocked him and Konohamaru, who knew she had been destroyed by Naruto. They reported back to him in Konoha.

Later, Team 10 was approached by Amado. He took Shikadai as a hostage, forcing Sai and a unit to approach him. The man asked to talk with Shikamaru, who was given communication via the Mind Body Transmission Technique. The man stated firmly that he wished to defect to Konoha, offering his full intel on Kara and its resources, their Ten-Tails, and even on the Ōtsutsuki. By order of the Hokage, Amado was brought in for questioning.

While reviewing the terms of Amado's asylum agreement, he raised the likelihood of Isshiki coming to Konoha to apply a new Kāma to Kawaki, so Sai was ordered to begin evacuation procedures for the civilians. As Sasuke and Naruto went to face Isshiki, Sai joined Shikamaru in taking Kawaki to an underground facility protected from Isshiki's Byakugan, ordering Amado to join them.

Chūnin Re-Examination Arc
In the anime, following Isshiki's attack, Naruto decided to host another Chūnin Exam to boost morale and promote more genin. Sai acted as a proctor, disqualifying one genin during the written exam, and also participated during evaluations during the second exam. With 10 genin passing the second exam, the proctors explained that a final round would pit them against each other in one-on-one fights. The next day, Sai checked on his genin, who taking after his Anbu teachings, were focused on getting one of their own to the end.

During the finals, Sai watched from the stands with Naruto and Shikamaru. The first match pitted Inojin against one of Sai's students, Hōki Taketori. Hōki ended up winning, crediting it to Sai's tutelage. He checked on both of them, and was glad to see both were in good spirits. During the third match, between Sarada and Chōchō, Sai commented with Naruto and Shikamaru the battle between best friends improved when Sarada stopped holding back.

The fourth match was Boruto vs Mitsuki. Unfortunately, the two failed to arrive on time, reluctantly making Sai and the other officials disqualify the two. Following the exams completion, it was noted how all the genin have shown noticeable improved, both in skill and as people. Later, Sai celebrated with his team Hōki's promotion.

Code Arc
Following Isshiki's defeat, Konoha learned that the last Kara Inner left, Code, was a fanatical followed of Isshiki's, who wanted revenge and was more powerful that Jigen without his limiters. The Five Great Shinobi Countries coordinated efforts to locate him before Code could abduct Amado to remove the limiters. Sai and his subordinates found Code's Claw Marks near the village's outer walls. Sai also reported that several Outers were captured, but their interrogations revealed nothing useful in finding Code.

Naruto Shippūden the Movie: Bonds
Sai, due to his ability to create flying mounts for himself with his Super Beast Imitating Drawing Technique, served a double function as a scout and first counterstrike against the Land of the Sky attackers by using taijutsu to jump and wreck different the Land of the Sky shinobi wing sets. He admits, soon after, that he is actually bored with the incompetence of the Sky ninja.

Naruto Shippūden the Movie: The Will of Fire
After being sent to scout the area, Sai is knocked out of the sky and is later found unconscious by Naruto. Although not officially given a mission, after recovering from previous injuries, Sai pursued the Konoha 11 on their way to Hiruko's base. Temporarily blinding San with a flashbomb, he picked up Naruto and Sakura in order to get them ahead of the following teams, leaving Shikamaru and his teammates to deal with San.

Naruto Shippūden the Movie: The Lost Tower
When Naruto and Yamato are taken into the seal Mukade broke, Sai saves Sakura from being pulled into it as well. When Naruto and Yamato reappear, they all go back to Konoha.

Road to Ninja: Naruto the Movie
The alternate world's Sai, compared to the Sai that Naruto and Sakura know, has more emotions within himself and is more outgoing. His passion for art is the same, the only difference is that his alternate self is horrible at it. Also, due to the alternate Sasuke still being part of Team 7, the alternate Sai never became a member of Team 7 nor does he know the others.

Trivia

 * As an Anbu member, Sai refers to Kakashi as his senpai out of respect.
 * According to the databook(s):
 * Sai's hobbies are drawing and calligraphy.
 * Sai wishes to fight Kakashi Hatake.
 * Sai's favourite word is.
 * Sai's favourite food is momen tofu, while his least favourite is mitarashi dango.
 * Sai has a frank, obedient and submissive personality.
 * According to character trivia from Boruto: Naruto Next Generations:
 * His attributes are: 140 in strength, 144 in intelligence, 155 in perception, 160 in dexterity, 150 in chakra, and 120 in negotiation.
 * He was also given a skill rating in these particular areas:
 * Art (Painting): ★★★★★
 * Disinformation: ★★★★☆
 * In the seventh character poll, Sai placed 12th place, alongside Sakura, with 2,188 votes each.
 * Between the end of the Fourth Shinobi World War and the events of The Last: Naruto the Movie, Sai changes his rank from "Anbu" to . Currently, it is not known what exactly this change implies.
 * In the anime, a dream version of Sai was still part of Root and was one of its best members, alongside Yūgao Uzuki, Hayate Gekkō, and Anko Mitarashi. He wore a standard-issue Anbu uniform with a black hooded cloak and a mask with abstract symmetrical designs.
 * Sai is the only known male character in the series to take on his spouse's surname upon marriage.

Quotes

 * (To Naruto) "The way you fight, are you a boy or a girl?"
 * (To Sakura) "A smile can get you out of a tough situation, even if it is fake."
 * (To Sakura) "I've drawn hundreds, maybe thousands of pictures so far… other pictures have the situation at the time, and the artist's feelings… like portraits have the person's name… but don't pictures usually have titles…? To be more precise, even if I try to give them titles, I just can't do it. I don't feel anything… they don't put me in mind of anything."
 * (To Sakura) "…I don't have any of what you'd call emotions."
 * (To Sasuke) "Even when I force myself to smile. It seems I'm the type of person who ends up being hated."
 * (About Sasuke) "…yet by just looking into his eyes, does this mean I fear Sasuke deep within my heart, despite being unable to recognise it myself…?"
 * (To his team) "Sai is the name I was given for this mission… I'm nobody. I am a tool for Lord Danzō. I don't exist."
 * (To his team about his adoptive brother) "We weren't connected by blood, but he did compliment me on my drawings quite a bit."
 * (To his team about the picture book) "The centre of two pages were the ones I wanted to show my brother the most, but since he's dead, I can't remember what I wanted to draw on them."
 * (To Kabuto) "If people change… then so can I. But some things never change. Bonds. I'd like to learn more about them."
 * (After finishing the picture book) "This is what I wanted to show my brother. The picture of our dreams."
 * (To Sakura) "Lately when I look at Naruto I've been able to feel it… his sadness. And when he thinks of Sasuke there's a heat coming from his gut and I know that's anger. For Naruto's sake, for Konoha's sake, we need to do something ourselves instead of always relying on him."
 * (To himself) "This… is what it means to have friends… I understand it perfectly… Naruto."