Itachi Uchiha

was an ANBU from Konohagakure's Uchiha clan before his defection, becoming an S-rank missing-nin and a prominent member of Akatsuki who was partnered with Kisame Hoshigaki.

Background
Itachi was born into the Uchiha clan to Mikoto and Fugaku and was praised by all as the best of his generation; a genius above all others. Even by the standards of the battle-adept Uchiha clan, Itachi's prowess far outshone them. However, not even his family, friends, or teachers could understand him. When he was only four, Itachi had already witnessed countless lives lost due to the Third Shinobi World War, which emotionally traumatised him and turned him into a pacifist.

During the Nine-Tails' attack on Konoha, Itachi held his infant brother Sasuke and told him that he would protect him no matter what as well as wondering where his parents had gone.

In the anime it was shown that during their childhood, Itachi made a game of collecting paw prints of cats from a domestic ones to lions with his brother. The last paw print to be collected was Nekomata's who Itachi had defeated and requested him to fight Sasuke with all his might when he got older.

At age 7, he graduated from the Ninja Academy at the top of his class after only one year, mastered the Sharingan at age eight, passed the Chūnin Exams at age 10, and became an ANBU Captain at age 13.

He was praised highly by his father, who saw the family's future in Itachi and hence inadvertently neglected his younger son. However, during this time Itachi showed great affection towards his little brother and even encouraged his father to come to the Academy enrolment ceremony for Sasuke, something their father had otherwise forgotten, by saying that he would not go to an important mission that would establish Itachi a place in the ANBU ranks, otherwise.

When the Uchiha clan began planning to overthrow Konoha, Itachi, as an ANBU, was tasked with spying on the village. Knowing that a coup d'état would only lead to another Ninja War; Itachi began spying on the Uchiha instead, passing on information to the Third Hokage and the other Konoha elders. During this time he began to act strangely, not attending the clan meetings, speaking out against the clan and becoming the prime suspect for the murder of his best friend Shisui Uchiha, who was drowned in the Naka River. In reality, Shisui had entrusted his remaining Mangekyō Sharingan to Itachi, the other having been taken by Danzō. Itachi assisted Shisui in making it seem that his eyes were destroyed. Due to this the clan lost hope in Itachi, and his father began shifting his focus to Sasuke instead. Meanwhile, the Third's attempts to negotiate a bloodless end to hostilities between the two parties were proving ineffective so, against the Third's wishes, Danzō Shimura and the Konoha Council ordered Itachi to wipe out the Uchiha clan.

Before the fateful night arrived, Itachi discovered the existence of Tobi — who was under the guise of a vengeful Madara Uchiha — and was attempting to rekindle the flames of war in Konoha. In return for not attacking Konoha, Itachi offered to help him claim vengeance against the Uchiha for turning their backs on him decades earlier; he agreed. Itachi slaughtered his entire clan overnight, sparing only Sasuke, because he could not follow through with the orders to kill him. Instead, he made himself out as a villain, who had killed their innocent family only to test his abilities. He told Sasuke that he was not even worth killing. In addition, Itachi told him, "You've always wanted to surpass me. That's why I'm going to let you live… if you wish to kill me, then hate me, despise me… and by all means flee, cling to your wretched life". Itachi also revealed to Sasuke where the secret meeting place of the Uchiha was hidden, and suggested that Sasuke go there to learn what the true history and purpose of the Sharingan was. He told him that in order to awaken the Mangekyō Sharingan, he had to kill the person he was closest to, and that when they met again, they should have the same eyes.

Sasuke managed to stand back up, awaken his Sharingan, and pursue Itachi. Upon reaching Itachi, he managed to knock off his forehead protector. Itachi shed a tear as he was picking up his forehead protector. He then proceeded to incapacitate Sasuke, who awoke in the hospital remembering only that which Itachi wanted him to. By doing all this, he wanted Sasuke to take vengeance on him and become a hero to Konoha, thus redeeming the Uchiha name. Hoping that his beloved little brother would someday be powerful enough to kill him, Itachi left the village as a traitor. According to Tobi, Itachi also had a lover, whom he killed during the Uchiha clan massacre. Knowing that Konoha would still want to eliminate Sasuke, Itachi pleaded with the Third Hokage to keep Sasuke safe. He also threatened Danzō to not harm Sasuke or risk Itachi revealing everything he knew about Konoha's secrets to enemy countries. Sasuke's safety was therefore secured and Itachi returned to his original plan of becoming infamous for his slaughter of the Uchiha clan.

Itachi joined Akatsuki in order to keep an eye on the organisation, along with Tobi, in case either ever acted against Konoha, all the while planning for his death at Sasuke's hands. While he was a member of Akatsuki, Itachi was approached by Orochimaru, who tried to steal his body to gain the Sharingan. Itachi trapped him in a genjutsu and severed his left hand as punishment, forcing Orochimaru to flee the organisation. He was partnered with Kisame Hoshigaki, who he initially greeted with threats after the latter tried to intimidate him. However, they eventually became good partners for sharing the common bond of having betrayed the people closest to them. Sometime after joining Akatsuki and forcing Orochimaru to flee, Itachi helped recruit Deidara by beating him in battle using only genjutsu, to which Deidara swore vengeance against Itachi.

At some point in time, Itachi contracted a fatal illness. He kept himself alive through the intake of various medicines and sheer "willpower", in the hopes of living long enough to die by Sasuke's hands.

Personality
Ever since his first appearance, Itachi had always been mysterious and acted as though he was hiding his true self. While flashbacks to his past showed that he was a compassionate brother and person, his later acts and claims made it seem that this was mostly just an act. But surprisingly, he genuinely was the compassionate brother he had once claimed to be, although he hid this from the rest of the Akatsuki to protect his beloved brother, Sasuke. Even at a young age, Itachi vowed he would protect Sasuke, while he was only an infant, at all costs just prior to the Nine-Tails' Attack on Konoha.

As a member of Akatsuki, he possessed incredible self-control of his emotions, constantly displaying an emotionless personality. He only showed surprise when opponents proved more powerful or skilled than he had expected, and even then he didn't lose his composure. He has also shown to have a sense of humor, as when he called his younger brother "Dr. Snakes" while fighting Kabuto Yakushi. He didn't possess any arrogance, and fully justified any statements he made about his power, even complimenting his opponents at times on their abilities. After his death, he realises that he shouldn't have tried to deal with Sasuke on his own and encourages Naruto to never forget his friends.

In addition to being an extremely powerful shinobi, Itachi had equally impressive intelligence, and was shown to be very wise, something even Tobi acknowledged. He was exceedingly sharp and observant to any situation at hand, as he was rarely surprised or caught off guard. He also displayed great intuition, as he was almost never deceived and even then almost instantly realised the truth. This intelligence could also be seen through Itachi's immense foresight, such as examples like the foreknowledge of Sasuke's defeat of Deidara and simultaneous survival, his own pre-meditated fatalist view of death by Sasuke's hand, and most recently the implantation of his own Kotoamatsukami-imbued crow inside Naruto were only some examples seen. Despite his status as a wanted criminal, and having wiped out his clan, Itachi took no enjoyment in violence or combat, instead preferring to avoid battle or, if this was not possible, end it as quickly as he could.

Itachi's only initial interest was in Akatsuki's goals, and his only loyalties appeared to be to the organisation and its members, seeming to put the organisation's success and secrecy before everything else, although this was all an act, as his true intentions for joining the organisation was to spy on it from within. Despite this, Itachi got along with his partner, Kisame, much better than most other Akatsuki members did with their own partners. Kisame appeared to have a deep loyalty to Itachi, immediately doing as he instructed and constantly looking out for his well-being. Itachi treated all of his fellow Akatsuki members to this same, more respectful personality, although his courtesy was rarely returned by the other members.

However, when he was in a genjutsu duel during his fight with Sasuke, he cruelly claimed he had only let Sasuke live so that he could take Sasuke's eyes and obtain his own Eternal Mangekyō Sharingan, after which he then claimed the Uchiha clan had been nothing but tainted and evil, since many members would kill their friends to gain the Mangekyō Sharingan, and would take another Uchiha's eyes to make its power permanent. Once the genjutsu was released, he called it his true self, implying his calm, emotionless personality was also a façade. This persona was later revealed to be only an act to ensure that he would die by Sasuke's hands, his love for his younger brother being the fundamental aspect of his personality.

In the end, Itachi put all of his faith in Naruto, who he notes as the person most determined to save and protect Sasuke. After hearing Naruto's answer to keep protecting Sasuke and everyone in Konoha, Itachi gave him some of his power. He was very grateful towards Naruto's determination to save Sasuke, and was smiling after hearing Naruto's response. Itachi even trusted him enough to bring Sasuke back to the light and refused to go see his brother after being resurrected by Kabuto, as he believes that Naruto, who has inherited Shisui's feelings, can stop Sasuke.

Appearance
Despite his status as an infamous shinobi, his appearance was not the most intimidating, apart from the intensity of his gaze. While living in Konoha, he would regularly have a gentle and caring look in his eyes, especially directed towards his younger brother. After joining Akatsuki, he would regularly have a stern look to them.

Itachi had dark eyes, black hair that hung near his cheeks (which grew slightly longer in Part II) to frame his face and kept the rest of it in a ponytail; which was later obscured by the high collar of the Akatsuki cloak he wore after joining the organisation. Being brothers, Itachi and Sasuke had a similar appearance but with subtle differences, so much so that Naruto nearly mistook Itachi for Sasuke when they first met. In comparison to his brother, Itachi's hair colour was slightly duller and had a softer flow to it; his skin was also slightly darker. Itachi's most distinguishing characteristics were the long pronounced tear troughs under his eyes; a physical trait he inherited from his father.

When he lived in Konoha, his casual clothes would consist of a black Uchiha shirt with a large Uchiha clan symbol on the back, and black pants with a weapons pouch strapped to his back. When on duty, he would wear the traditional ANBU uniform, although he was never shown wearing a mask. As a member of Akatsuki he wore the traditional Akatsuki cloak and usually kept the centre of it buttoned down, as well as a slashed Konoha forehead protector. At other times, he would unbutton the top half of his cloak and rest his left arm there, rather than in the sleeve. After his cloak was incinerated by Sasuke's Kirin during their fight in Part II, it was revealed that he wore similar clothes to that of the rest of the Akatsuki underneath it consisting of a blue v-neck T-shirt (where as most other Akatsuki members wore a sleeveless shirt) and blue pants with a body mesh under the T-shirt, and a white sash around his waist on the outside of the shirt much like a tunic. Like almost all members of Akatsuki, he wore the headband of his home village with a horizontal line gouged through it to symbolise his broken ties with the village. On his right ring finger was his Akatsuki ring, which was red in colour and bears the kanji for. He also wore dark purple nail polish on his fingers and toes and a necklace with three metal circles or rings on it.

After being resurrected, Itachi's eyes appear to have black sclera like the other shinobi that Kabuto Yakushi resurrected, except for his activated Sharingan. He is also clad in a dark-red cloak.

Abilities
Even at a young age, Itachi's intellect and talent showed their brilliance in everything he did, as even his teachers said his progress hardly required any help. In the few battles he had been seen in since the start of the series, Itachi was shown to be an incredibly powerful ninja, as demonstrated by his ability to easily defeat several powerful shinobi. Despite his pride in his own strength, Kisame Hoshigaki, Itachi's partner in Akatsuki, acknowledged Itachi as the stronger of the two. Tobi said that Itachi never ceased to amaze him. However, despite his impressive abilities, he never underestimates his opponents, given his praise of Jiraiya, saying the best he could do against him was a stalemate. The only thing that Itachi was lacking was his chakra reserves, which were below average, presumably due to his illness. Regardless, even with his fatal illness and his own preplanned death as inhibitions, Sasuke was still unable to defeat Itachi, who instead succumbed to his disease and the strain of maintaining his Susanoo on such low chakra. Despite the stress his body was under that was slowly killing him he was still able, in his last moments, to perform his own fūinjutsu.

Itachi's skill with kunai was such that he could perfectly hit a set of nine targets, one of which was in a blindspot hidden behind a large rock by hitting one kunai with another making it hit the target; During his fight with Nagato, he was able to find blindspots and blind the latter's summons despite the shared field of vision granted by the Rinnegan. He was also very skilled with shuriken, Sasuke stated that he was best with shuriken, even more skilled than their father. During their fight at the Uchiha Hideout, Itachi was able to counter every one of Sasuke's shuriken with his own.

Being a technical pacifist due to his traumatic experiences from the Third Shinobi World War, Itachi did not actively take part in battle, typically only acting in self-defence and trying to incapacitate his enemies instead of killing them if possible.

Taijutsu
Itachi possessed very high-level taijutsu skills despite not specialising in it. This was demonstrated when he easily dispatched three fellow Uchiha, all of them his seniors as well as members of the Konoha Military Police Force. In Part I, he stopped Sasuke's Chidori with one hand and brutally beat him during their reunion in the Land of Fire despite Sasuke's extensive taijutsu training for the Chūnin Exams. His skill in taijtusu was great enough to keep up with Naruto Uzumaki in his Nine-Tailed Chakra Mode and Killer B, even though he had to retreat when facing both together.

Itachi was also noted to be immensely fast, particularly with his hand movements. This extended to collectively weaving both hand seals and throwing weapons, as he was able to reveal a set of shuriken and then suddenly perform a ninjutsu, making it appear as if he could perform his techniques without seals. In terms of mobility, he is able to cover considerable distances fast enough to appear like teleportation.

Ninjutsu
Itachi was a master of all the Uchiha clan's techniques, along with the Sharingan, and had great prowess with all of the three main types of jutsu. When battling against Kakashi, Kurenai, and Asuma, Kakashi commented that Itachi wasn't fighting with even half of his strength. Itachi's techniques also often involved usage of crows, both in ninjutsu and genjutsu. This is seen amongst others with his creation of a clone that dissolves into crows and using crows to hide shuriken in them or creating shadow clones with the ability to explode.

As traditional to the Uchiha clan, Itachi could use Fire Release techniques including the clan's Fire Release: Great Fireball Technique and was able to infuse shurikens with fire. The heat of his Great Fireball Technique is great enough to bother even Samehada. He was also shown to use Water Release techniques such as creating a drilling mass of pressurised water.

Sharingan
Being of the Uchiha clan, and as noted by Kakashi, Itachi was a true successor of the Sharingan, having fully developed and mastering it by the time he was eight years old. From a stationary position, he would study an opponent's movements with his Sharingan and respond accordingly, often with a genjutsu. Itachi was often praised for his prowess with genjutsu and could even cast it by merely pointing at someone. He could also turn an opponent's genjutsu against them using it to his own advantage. According to Ao, he could also use his genjutsu to take control of other individuals from a long distance. Most of his genjutsu are derived from the Sharingan, but regardless of whether they are or not, all of them cause powerful mental trauma.

Using his Sharingan, he could also perfectly fake Shisui Uchiha's suicide letter after he had supposedly killed him. He had trained so much with his eyes that he had reached the stage where he could have his Sharingan activated for extended periods of time, with minimal drain on his chakra levels.

Mangekyō Sharingan
Itachi possessed the Mangekyō Sharingan, which increased his already great power, and enabled him to use his most powerful techniques. With his left eye, he could use Tsukuyomi, a genjutsu that traps an opponent's mind in an illusory world, torturing them for what seems like days to the victim, in a matter of seconds. With his right eye he could use Amaterasu, a ninjutsu which allowed him to create black flames, that he could direct by moving his eye, to burn through anything in its path, including fire itself. His final technique was Susanoo, the, a technique that uses both eyes to manifest itself as a spectral being. It wielded the Sword of Totsuka, an ethereal sword with the ability to seal anything it pierces into the gourd that serves as its hilt, and Yata Mirror, a shield that could reflect any attack. Zetsu, a fellow Akatsuki member, stated that Itachi's mastery of the Sharingan, combined with the legendary weapons of Susanoo, made him nearly invincible. With Susanoo he was also able to use his most powerful long-ranged attack, the Yasaka Magatama.

Despite his mastery of the Mangekyō Sharingan, Itachi suffered greatly from its side effects. Each of the techniques bestowed by the Mangekyō Sharingan required vast amounts of chakra to perform, and they left Itachi fatigued afterwards, to the point of requiring him to deactivate his Sharingan altogether, something that he did not usually need, three uses of which seem to have been enough to bring him to this in Part I. The other side effect was that his eyesight would worsen as time passed since the awakening of the Mangekyō Sharingan, and the degradation would only increase after every time he used it, which would lead him to eventually go blind from its power, with his Sharingan forever sealed away. By the time Itachi activated his Mangekyō Sharingan during his final fight with Sasuke, Itachi's eyesight was so badly damaged, that Sasuke appeared to be only a messy blur and was so close to blindness that by the time he activated Susanoo in his final fight, both Sharingan had lost the Mangekyō design in them, with only the red iris remaining.

Intelligence
Itachi has been shown to possess an extremely high intellect, being able to deduce the inner workings and weaknesses of incredibly powerful techniques, even while under pressure. Itachi appears to have deduced a method of defeating the Summoning: Impure World Resurrection technique altogether. His intellect was such that he was able to not only orchestrate the entirety of his battle against Sasuke years in excess of its actual occurrence, but restrain himself throughout the battle in order to bring about his intended outcome. He was even able to account for the possibility that his plan wouldn't go as intended by sealing his power into Sasuke and placing a special crow inside of Naruto Uzumaki in the eventuality that Sasuke turned against the village. Even Tobi himself admitted that if he hadn't kept a few secrets from Itachi he'd be dead.

Search for Tsunade Arc
After the Invasion of Konoha and the death of the Third Hokage, Itachi and Kisame infiltrated the Konoha to find Naruto Uzumaki, the container of the Nine-Tailed Demon Fox. Before searching for Naruto, the two quickly stopped for tea after a suggestion from Kisame. While there, however, their uncommon clothes drew the attention of Kakashi Hatake, who had Asuma Sarutobi and Kurenai Yūhi follow them. Itachi and Kisame nearly managed to escape the village, before Asuma and Kurenai managed to catch up with them in time.

When the two revealed their identities, Itachi and Kisame were quick to battle Asuma and Kurenai after they refused to leave. Despite their high ranks of jōnin, Asuma and Kurenai stood little chance against the two Akatsuki members. However, the arrival of Kakashi managed to keep Asuma and Kurenai from receiving any major injuries. After a short skirmish with Kakashi, Itachi activated his Mangekyō Sharingan and used Tsukuyomi to attack Kakashi's mind and spirit, which afterwards left the latter confined to bed for several days. After Kakashi revealed he had knowledge of Akatsuki, Itachi ordered Kisame to kidnap Kakashi and to kill Asuma and Kurenai. However, Might Guy then showed up, revealing that he had already told the ANBU about the two Akatsuki members' presence. Itachi and Kisame retreated, saying that they didn't want to start a war.

Itachi and Kisame tracked Naruto to a hotel where he was staying with Jiraiya at the time. Uninterested in provoking a Sannin, Itachi used a genjutsu on a pretty woman to draw Jiraiya away from Naruto. Taking the chance, Itachi and Kisame confronted Naruto, although, at the very same moment, Sasuke arrived to seek vengeance on his brother. Itachi handled his brother with ease while Kisame and Naruto watched, although Jiraiya arrived in time to save the two boys, having not fallen for the hypnotised woman's charm as he knew that pretty women did not usually show interest in him.

Jiraiya immediately asked Itachi and Kisame if their real goal was kidnapping Naruto. They confirmed this and Itachi understood that Jiraiya was the one who had told Kakashi about Akatsuki. Although Jiraiya wished to fight them himself and prevent others from getting hurt, he honoured Sasuke's feelings, and allowed him to fight Itachi instead. Itachi, however, only proved Jiraiya wrong in letting Sasuke fight by using his Mangekyō Sharingan on his younger brother, thus reaffirming his need to get stronger. Jiraiya saved Sasuke in time by using the Summoning: Toad Mouth Bind, which transformed the entire hotel hallway into a toad's oesophagus to trap Itachi and Kisame. Despite Jiraiya's claim that no-one had escaped this technique before, the two Akatsuki partners managed to evade capture and death using Itachi's Amaterasu, which left him exhausted.

Although he was actually supposed to capture Naruto, Itachi's only reason for returning to Konoha after the death of the Third Hokage was to remind Danzō and the other two village elders that he was still alive and not to harm his younger brother.

Kazekage Rescue Arc
While Akatsuki was sealing the One-Tailed Shukaku, they discovered that Team 7 and Chiyo were en-route to their location. Itachi volunteered to distract them, so Pain used the Shapeshifting Technique on Yūra to create a body-double for Itachi. The lookalike, under Itachi's control, engaged the Konoha ninja. He was impressed by Naruto and Kakashi's improvements in strength but, because the clone had only a portion of his ordinary strength, it was killed by Naruto's Big Ball Rasengan. Nevertheless, he was able to buy enough time.

Itachi Pursuit Arc
As Sasuke was defeating Orochimaru, Itachi sensed something odd. Kisame asked him what was wrong, to which Itachi replied, "No, it's nothing." Following Kisame's capture of the Four-Tails, Itachi and Kisame met with the rest of Akatsuki. There, they discovered that Sasuke, after being trained by Orochimaru for two and a half years, had killed his teacher. Sometime after the Four Tails was sealed, Zetsu informed them that Sasuke had been killed by Deidara's C0. Kisame asked Itachi if he was upset that Sasuke's death had left him as the only Uchiha because in the rain he looked as if he were crying. However, Itachi remarked that Sasuke was not dead, and alluded to the fact that there was still another Uchiha regardless.

Knowing that his end was near, one of Itachi's shadow clones confronted Naruto, who was looking for Sasuke. Although he claimed he wished only to talk, Itachi was forced to defend himself against Naruto's attacks. After fending off Naruto, Itachi asked why he showed so much interest in Sasuke, a traitor to Konoha. Naruto replied that he was more of a brother to Sasuke than Itachi had ever been, and that he would do whatever it took to bring Sasuke home. This caused Itachi to give a small smile, followed up by asking if he would always feel that way, even if Sasuke attacked Konoha. Naruto replied only that, if that happened, he would stop Sasuke without killing him and protect the village. Content with this answer, Itachi gave some of his power to Naruto, by forcing him to swallow one of his crows, and hoped he would never have to use it.

After his business with Naruto was done, another of Itachi's shadow clones went to meet with Sasuke. Sasuke exhibited a dramatic improvement in his abilities during their confrontation, so Itachi agreed to have their final battle at the Uchiha Hideout. He waited there for Sasuke's arrival, instructing Kisame to not let the other members of Sasuke's team interfere with their combat. Itachi and Sasuke met face-to-face and, while exchanging genjutsu, had a conversation about the Uchiha, Madara Uchiha, and Itachi's "true" motives of wanting to take Sasuke's eyes. When Sasuke managed to escape Itachi's Tsukuyomi, the genjutsu battle ended and the ninjutsu battle began.

Itachi used Amaterasu, but Sasuke protected himself by shedding his skin, a technique he was able to use due to Orochimaru being sealed within him. Using the shed skin as a decoy, Sasuke went below and fired a Fire Release: Great Dragon Fire Technique at Itachi's direction above although he only managed to burn away one of Itachi's sleeves. Out of chakra, he told Itachi about his final jutsu that, like Amaterasu, is impossible to avoid. Sasuke then used his trump card, on Itachi, who got his Akatsuki cloak burned off as a result.

However, Itachi managed to survive by using Susanoo to defend himself. With Kirin having expended all of Sasuke's chakra, Orochimaru was able to assume control and violently appeared through his Eight Branches Technique. However, Itachi was easily able to cut off the seven snake heads, leaving only one behind whose mouth Orochimaru appeared out of and thanked Itachi for pushing Sasuke so far, in the process setting him free and allowing him to take control of Sasuke's body. Itachi, however, stabbed Orochimaru with the Totsuka sword to seal him away with Susanoo, thereby removing the cursed seal from Sasuke's body.

As Itachi began to weaken, thus weakening Susanoo, Sasuke saw an opportunity to strike, but in vain, as Susanoo was still able to protect Itachi. His last option gone, Sasuke was pushed against a wall and left helpless as Itachi walked up close to him and seemed to be reaching for Sasuke's eyes. However, he instead poked Sasuke's forehead and smiled before saying, "Forgive me Sasuke… …It ends with this."; this was a reference to Itachi constantly poking Sasuke on the head when they were younger. With that act, Itachi finally gave in to his fatal illness, which he had been using medication and sheer willpower to fend off, and died.

Konoha History Arc
In the anime, three years ago before Sasuke's defection from Konoha, Nekobaa mentioned about Itachi, but was stopped by Sasuke from talking about him. After Sasuke defeated Nekomata, he told Sasuke that Itachi had defeated him in the past along with his ninja cats and requested that Nekomata fight Sasuke with all his might when he got older.

Later, Sadai, an assailant who entered the Land of Fire to capture Naho, mentioned to Sasuke about Itachi, the Uchiha Clan Massacre, and even about Sasuke for being weak, which led to Sasuke defeat Sadai and punch him severely.

Confining the Jinchūriki Arc
Itachi was summoned by Kabuto Yakushi through the Summoning: Impure World Resurrection, along with Nagato, Kakuzu, Sasori, and Deidara as a demonstration of power to Tobi.

Shinobi World War Arc
As the Fourth Shinobi World War against the Allied Shinobi Forces commences, Itachi is mobilised alongside Kakuzu, who carries an immobile Nagato on his back. Later supporting the latter as they walk, the now isolated pair continue throughout the night, conversing about Akatsuki. Itachi then remarks that their two dōjutsu together could achieve anything, which is likely why their summoner would wait for the opportune moment to use his abilities. After pausing at a shrine and discussing Kabuto's influence on Tobi's plan, they march onwards till dawn, when they encounter Naruto and Killer B.

Surprised by Naruto's growth and subjugation of the Nine-Tails, Itachi attempts to ask him something, but he instead attacks the pair involuntarily with his Fire Release: Great Fireball Technique. Discerning Kisame's death, from B's possession of Samehada, he engages Naruto directly. Exchanging both dialogue and blows, Itachi is shocked and disappointed by his brother's decision to destroy Konoha, while learning Tobi was aware of the truth behind the Uchiha clan massacre. Imploring Naruto to keep the details secret, to maintain his clan's honour, he then entrusts dealing with Sasuke to him. As Itachi confronts B, he catches him in a genjutsu, after using his Fire Release: Phoenix Sage Flower Nail Crimson technique. However, fending off several attacks, he retreats atop Nagato's summon and activates his Mangekyō Sharingan, wondering what would happen as he does. Much to Naruto's shock, the crow Itachi had placed inside him emerges.

As Itachi and the crow's eyes meet, he seemingly prepares to attack Naruto with Amaterasu, however, it instead hits Nagato's other summon. Realising his plan had succeeded, Itachi turns on Nagato and engulfs him in black flames, before leaping towards Naruto. He then explains how he had implanted the eye that he received from Shisui into the crow to use Kotoamatsukami with the embedded command "protect Konoha", which is why he was able to override Kabuto's control. Informing them that the crow had been rigged to react to his Mangekyō Sharingan and was originally intended for Sasuke, in the possibility that he attacked Konoha after transplanting eyes to gain the Eternal Mangekyō Sharingan, Itachi expresses his belief that only Naruto could stop his brother. Asked by B why he didn't just use it on Sasuke from the beginning, he reveals that he was unable to because excluding augmentations, such as Hashirama Senju's chakra, Shisui's Mangekyō would take a decade to regenerate. He also told them that he had other intentions behind his death. Grateful that Sasuke had a friend like Naruto, the three are then assaulted by Nagato's large scale Shinra Tensei, who was now under Kabuto's full control.

With both of the jinchūriki in grave danger at Nagato's hands, Itachi intervenes and frees the two using his incomplete Susanoo. It is later revealed that he had previously blinded both the King of Hell and the chameleon summon with a barrage of kunai, to approach undetected despite the Rinnegan's shared vision. Releasing them from his Susanoo's grasp, the three begin to be drawn upwards by Nagato's Chibaku Tensei. After careful analysis, Itachi surmises that attacking the sphere at the centre of the technique would effectively dispel it, so he proposes that they use the attractive force to direct their strongest long-range techniques at it. Using Yasaka Magatama in combination with the others' attacks, they confirm his conclusion and before the dust settles, Nagato finds himself impaled by Itachi's Sword of Totsuka. Disclosing that the sword would seal him, he states that if Nagato had any last words, he should impart them now.

After Nagato is sealed, Itachi states that he would deal with the Summoning: Impure World Resurrection technique as he had already formulated a plan, allaying Killer B's concerns by reiterating that every technique had a weakness. However, when Naruto decides to stop the war on his own, Itachi tells him that despite becoming stronger, he is forgetting all those who he wanted acknowledgment from and that with those egotistical thoughts, he would eventually become like Tobi. Reminding him that his father became Hokage because of Kushina and those around him, he states that if Naruto has the same dream, he should not forget his friends. Itachi then incinerates his crow, stating that the eye was useless as it could not be reactivated for another decade and that Naruto, having inherited Shisui's feelings, could stop Sasuke without it. Refusing to see his brother, after realising that he tried to do everything on his own and still failed, he resolves to leave Sasuke to his friends instead. Asking B to look after Naruto, Itachi departs.

Encountering Sasuke while on his way to stop Kabuto's technique, Itachi presses on nonetheless, refusing to acknowledge his now pursuing brother. This causes Sasuke to manifest a hand of his Susanoo in an effort to catch him, but Itachi simply uses his own Susanoo to deflect this, before noting his shock that Sasuke now possessed the same technique as him. Bombarded by a series of questions, Itachi reveals the true reasons behind Sasuke's survival of the massacre, citing Sasuke's childhood innocence and his own desire to be punished for the act by a fellow Uchiha to him. Expressing his regret about the path Sasuke had chosen and blaming himself somewhat, he resolved to talk no further as he was already dead, which leads Sasuke to retort that Itachi was still running away from him even in death. Itachi breaks his silence to refute this, stating that he was not running away but that there were important tasks that he needed to accomplish, in particular stopping the Summoning: Impure World Resurrection technique.

Attempting to obstruct Sasuke using a flock of summoned crows while he advances, Itachi soon destroys a wall with his Susanoo's arm, so as to confront Kabuto. Congratulated upon finding him despite an erected barrier, Itachi informs Kabuto that whilst under his control, he could vividly feel the source of where his chakra came from. As Kabuto declares that he couldn't be killed if Itachi sought to stop the technique, sensing Sasuke behind him, Itachi exasperatedly muses that things weren't proceeding as he intended.

Listening as Kabuto tries to inveigle Sasuke into helping him, Itachi deflects the shuriken that Sasuke throws at Kabuto telling his little brother that Kabuto had to be kept alive or else the Summoning: Impure World Resurrection technique would never be stopped. He then stated that he would use Tsukuyomi in order to find out how to stop the technique then force him to stop it. He then tells Kabuto — who was reciting the invulnerability of the technique — that every technique had a weakness and in this case, it was him. As Sasuke joins forces with him, he promises his brother that this time he would keep his promise and speak to him once Kabuto was stopped.

As Kabuto draws his hood over his face, claiming that he was an introvert, Itachi tells his brother to be careful of the snakes since they seemed to be able to clearly sense them. After being informed of some of the snakes' abilities, Itachi teases his little brother calling him "Dr. Snake". As Kabuto has the snakes attack them, the two brothers activate their Susanoo and blocks the attack. Telling his brother not to be so crass after he cuts the snakes' heads off. As Kabuto manages to elude them, Itachi tells his brother once again to be careful because he wasn't able to tell where the real Kabuto was due to him shedding his skin. Shocked after hearing Kabuto's revelation that he had found the Dragon Earth Cave, Itachi confirms that several of his suspicions were right after all. He then prepares himself as Kabuto attacks them with the Sage Art: White Violent Technique.

Legacy
After the fight Tobi collected Sasuke, tended to his wounds, and tried to befriend him when he awoke. When he removed his mask while doing the latter, Sasuke reflexively used Amaterasu on him. After quelling the flames, Tobi explained that the Amaterasu had been sealed in Sasuke by Itachi, intended to protect him from Tobi and whatever he might say. Sasuke was perplexed, so Tobi went onto detail the history of the Uchiha clan, and the truth behind Itachi's life. Towards the end of his story, he explained that Itachi had been dying of disease, but had kept himself going with medicine so that he could die by Sasuke's hands, stating that if Itachi had battled with all his strength they wouldn't be having that conversation. He also stated that Itachi had pushed Sasuke to his limits during their battle to draw out Orochimaru, so that he could remove the latter's influence from his beloved little brother.

Sasuke was unwilling to believe the story. Tobi persisted, saying that Itachi had entrusted the Uchiha name to Sasuke, hoping he would rebuild the clan on a new foundation of honour and nobility. For the sake of Konoha, and for Sasuke, he had been willing to die as a traitor and criminal. He had traded honor for disgrace and Sasuke's love for his hatred, and even then he had died smiling. Finally accepting the truth, Sasuke was crushed to find that the brother he had hated had actually been looking out for him all along. Upon realising the truth, he awakened his Mangekyō Sharingan and resolved to take vengeance against Konoha for the massacre of his clan and the fate they placed on his brother, regardless of Itachi's attachment to the village. He also agreed to start working with Tobi and, as a result, is classified as an international criminal, something Itachi had tried to prevent by sacrificing everything he had, but even that had not been enough to deter Sasuke.

Danzō confirms that Tobi's allegations that Itachi massacred the Uchiha for the coup are indeed true during his fight with Sasuke. Danzō states that Sasuke's actions destroy the importance of Itachi's legacy of a man who loved his village and was willing to sacrifice much for it.

Sasuke initially refused to transplant Itachi's eyes into his own sockets, due to the two of them having completely different visions of the future. However, after his reckless overuse of his own Mangekyō Sharingan from battling Killer B, A, Danzō Shimura and Team 7, Sasuke's eyesight had greatly deteriorated. As such, he decided to abandon his refusal, and take Itachi's eyes to use them to destroy Naruto at full power. The transplant was then commenced by Tobi, and Sasuke stated that he felt Itachi's power flowing through him.

After being resurrected by Kabuto and freeing himself from the control of the technique, Itachi helped both Naruto and Killer B defeat and seal away Nagato. After that, Itachi claimed to have a plan to stop the Summoning: Impure World Resurrection, becoming an ally of the Allied Shinobi Forces.

Trivia

 * can be translated as "weasel".
 * Itachi ranked highly in the Shōnen Jump popularity polls for the series, continuously placing in the top ten and reaching sixth place once. In the latest popularity poll, he rose to fifth place.
 * He and Kisame were the first active Akatsuki members to appear.
 * Itachi and Kisame made a brief cameo appearance in the Hidden Leaf Village Grand Sports Festival!, where they were standing in line to use the bathroom, along with many other random characters.
 * According to the Third Naruto Databook:
 * Itachi's hobby was visiting traditional Japanese cafés.
 * Itachi wished to fight Sasuke.
 * Itachi's favourite foods were cabbage and onigiri with seaweed in it, while his least favourite was steak.
 * Itachi had completed 340 official missions in total: 53 D-rank, 152 C-rank, 134 B-rank, 0 A-rank and 1 S-rank.
 * Itachi's favourite word was.
 * Itachi had always poked his younger brother, Sasuke Uchiha, in the forehead when they were younger, saying . This is referred to very poignantly with Itachi's last words, as he pokes his brother's forehead again and says,
 * Itachi is tied with Jiraiya for having the highest stat total in the databooks.
 * Itachi is one of the few people who were aware of Naruto's heritage, knowing both his father and mother.

Quotes

 * (To Sasuke)
 * (To Sasuke) "Being skilled isn't all that's it's made out to be. When you're strong, you become arrogant and withdrawn. Even if what you sought after was your dream."
 * (To Sasuke) "You and I are flesh and blood. I'm always going to be there for you, even if it's only as an obstacle for you to overcome. Even if you do hate me. That's what big brothers are for."
 * (To Sasuke as an infant) "Don't cry, Sasuke. Your big brother is here to protect you, no matter what happens."
 * (To Nekomata) "Growth occurs when one goes beyond one's limits. Realising that is also part of training."
 * (To the Uchiha clansmen) "I've had enough, there's no hope left for this pathetic clan."
 * "The people of this clan are all the same. You focus on the trivial, and lose sight of what's most important. Change is impossible, in this fog of ignorance. How can we evolve when regulation is all we know?"
 * "You hold onto the organisation and your clan name. These things limit us and limit our capacities… These things deserve to be shunned. It is foolish to fear what we've yet to see and know!"
 * (To Sasuke) "Foolish little brother, if you wish to kill me, hate me, detest me. And yet survive in an unsightly way. Run, run and cling to life, and when you have the same eyes as mine, come to me."
 * (To Kisame) "Those who turn their hands against their comrades are sure to die a terrible death."
 * (To Kisame, after he related the story of the sharks) "We are humans, not fish. We don't know what kind of people we truly are until the moment before our deaths. As death comes to embrace you, you will realise what you are. That's what death is, don't you think?"
 * (To Naruto) "You're still acting like a child. You're living in a fantasy world. You need to come to terms with the fact that you, as a ninja, will be forced to make impossible decisions like this."
 * (To Sasuke) "People live their lives bound by what they accept as correct and true. That's how they define "reality". But what does it mean to be "correct" or "true"? Merely vague concepts… their "reality" may all be a mirage. Can we consider them to simply be living in their own world, shaped by their beliefs?"
 * (Last words to Sasuke)
 * (To Naruto) "I'm grateful that my little brother has a friend like you."
 * (About Shisui's teachings to him) "Self-sacrifice… A nameless shinobi who protects peace within its shadow… That is a true shinobi."
 * (To Naruto) "Your dream was your father's dream, wasn't it? Remember this well then. The village did not acknowledge him because he became Hokage. He became the Hokage because the village acknowledged him."
 * (To Sasuke) "You didn't know anything about what was happening at that time… You did not know anything about the Uchiha clan's foolish idea… you were just a kid. Plus it wasn't for your sake alone… I also thought that one day I should be judged for the crimes I committed by an Uchiha like you, for that sake I used the hatred within you… and that's why I failed. The only thing I did was, giving the hatred to you and making you flee the village… I turned you into a criminal."
 * (To Sasuke) "You've learnt a lot... Dr. Snake."