Itachi Shinden Book: Light and Darkness

is an arc of the Naruto: Shippūden anime. It covers episodes 451 to the first part of 458. The arc focuses on Itachi Uchiha's life leading up to and following the Uchiha Clan Downfall. The arc serves as an intermission to the very start of the Kaguya Ōtsutsuki Strikes arc.

The arc draws its name from two Naruto Shinden novels: the Book of Bright Light and Book of Dark Night. Other than the name, the arc has little differences from the novels.

Summary
When Itachi was four-years-old, he witnesses death and destruction during the Third Shinobi World War. Itachi comes across a wounded Iwa shinobi and tries to help him but is attacked, forcing Itachi to kill him. When he asks his father about this, Fugaku explains what war is. While attending a memorial service for those who died, some of the Uchiha are angry that Kakashi received Obito's Sharingan, but Fugaku tells them that they must respect Obito's wish to give it as a gift for Kakashi. Itachi meets Orochimaru who says living without eternity is pointless, which makes Itachi question the way to live. Itachi even throws himself off a cliff before deciding to save himself and befriends a crow. Sometime later, Mikoto tells Itachi that he is going to be an older brother and Sasuke is born the following summer. Itachi comes to cherish the bond he feels with his younger brother.

Three months later, Tobi summons the Nine-Tails within Konohagakure. Itachi protects Sasuke during the rampage as he tries to get them to a shelter. He finds Izumi and helps get her to the shelter with him and Sasuke. Afterwards, they attend the funeral for those who died during the attack and Izumi thanks Itachi for saving her. Danzō oversees the rebuilding of the village and relocates prominent clans, including having the Uchiha clan move to the outskirts of the village. This displeases the Uchiha because of the village elders suspecting the clan was responsible for the attack, but Fugaku tells them that they have no choice but to agree because they can't be the only voice of dissension. Itachi begins training with his father and quickly masters the Fire Release: Great Fireball Technique.

When Itachi is six, he enrols in the Academy, along with Izumi, Saisu Kamano, Hana Inuzuka and Maruten Akimichi. Itachi excels in it and asks for his father to teach him more jutsu, as he deems the ones from the Academy too easy. Itachi earns the admiration of all the girls and jealousy from all the boys. However, when Itachi defends the bullies from an older student, they start to admire him, much to his dismay. After a year in the Academy, Itachi starts to question the meaning of a shinobi and the village. He sends a shadow clone to the Academy and has shurikenjutsu training, during which he meets Shisui, whom he bonds with due to their mutual desire to stop war and violence. When the teachers discover Itachi mastered the Shadow Clone Technique, he is offered an early graduation. Itachi accepts with his parents' consent and becomes the youngest student to graduate from the Academy at age 7.

Itachi is assigned to Team 2 with Tenma Izumo and Shinko Inari. Three years pass, as Itachi becomes aware of the rift between the Uchiha and the village, but points out to his father that Fugaku is a proud, respected leader of the Uchiha. After a mission, he meets with Izumi, who offers to share dumplings with him. Itachi declines but is unable to resist, as it is his favourite food, and Izumi is amused of Itachi's weakness for sweets. She then apologises for not getting him a graduation present and he tells her not to worry over it. Itachi and his team-mates are assigned by Nekobaa to find a ninneko. Tenma is the most invested in the mission because the cat's whiskers are the main ingredient for the medicine needed for his father's illness. His team-mates are incapacitated and Itachi saves Tenma, who cuts off the whiskers. After completing the mission, Itachi apologises for the whiskers getting cut off and Nekobaa accepts the apology. On their way back to the village, Shinko scolds Tenma for not thanking Itachi for saving him, and at Itachi for not considering them as friends and for acting like they were only on a mission. Itachi becomes surprised when Tenma says he owes Itachi. As he recalls this moment, Itachi remembers when Tenma was killed by a masked man and in this painful memory, activates his Sharingan. When he shows it to Sasuke, his brother responds by hugging him and Itachi wonders if Sasuke will awaken his.

Tenma's death weighs heavily on Itachi, who is angry that his father cares more about the latter awakening the Sharingan than witnessing his friend's death. Itachi and Shisui go on a three-part training exercise in the Forty-Fourth Training Ground. They find three members of Root attacking a Konoha Anbu for information on a traitor. Itachi sets up a trap for the Root members, who reveal the Anbu is a water clone and they already poisoned the real one. Itachi sets up a trap for the Root but is injured when his Sharingan fails to respond quickly. Shisui defeats the Root, who retreat. Itachi and Shisui then discuss how Itachi needs to improve his Sharingan's perception and abilities before returning to the Uchiha Compound. Before long, Itachi joins the Anbu and is promoted to captain.

Itachi begins acting as a double spy for the Uchiha and the village. As the tension between the two escalates, the clan begins plotting a revolt to overthrow the elders. When Shisui fails to stop the clan from changing their mind about revolting against the village, Shisui entrusts his remaining left eye to Itachi and commits suicide by jumping off a cliff. Witnessing this causes Itachi to awaken the Mangekyō Sharingan. Most of the clan suspects Itachi murdered Shisui and warns him to never betray the clan, which causes Itachi to lash out at them for caring more about the clan than the village. After his promotion, Itachi meets Danzo and is given a series of assassination missions, as well as being involved on spying for the clan. Fugaku takes Itachi to the Stone Tablet, and reveals he awakened his own Mangekyō Sharingan during the war. Fukagu explains he kept it a secret because it would lead the villagers to suspect he controlled the Nine-Tails and he intends to lead a "bloodless" revolt, and reveals through genjutsu that he could have used drastic measures to revolt by kidnapping Naruto and releasing the Nine-Tails.

Itachi informs the elders of what he's learned and Hiruzen opts to make peaceful negotiations with the Uchiha. However, Danzō tells Itachi to either go along with the revolt and die with his family or slaughter the entire clan but spare his brother. Itachi chooses the latter and finds the masked man hiding in the shadows, and asks for his assistance. On the night of the massacre, Itachi kills everyone within the Uchiha compound while the masked man kills everyone at the Konoha Military Police Force headquarters. Izumi tries to fight the masked man, but she is easily defeated and cries out for Itachi to save her before she is killed. Itachi encounters Fukagu's shadow clone, who questions his actions. Itachi expects to fight his father, but finds both of his parents waiting for him and accepting his decision to side with the village. Although they don't hesitate to stop him, they tell him they are proud of him and ask him to take care of Sasuke before Itachi sadly kills them. Afterwards, he and the masked man part ways and Itachi reports to Hiruzen, who is saddened for what happened and appreciates Itachi for saving the village. Itachi leaves with the masked man, who is going by the name Tobi, to join the Akatsuki and finds out that Orochimaru is also a member. After accepting the ring and cloak, Itachi is partnered with Jūzō Biwa, a former member of the Seven Ninja Swordsmen of the Mist.

Although Juzō says he is not interested in Itachi's reasons for joining the Akatsuki, they talk about their specialties. They carry out assassination missions and Pain informs the Akatsuki about the plan to collect the tailed beasts. Juzō and Itachi are assigned to go to the Land of Water, much to former's dismay, as it is his homeland. On their way there, Juzō tells Itachi to kill him if he is captured. When they arrive, they are confronted by the Mizukage and his bodyguards. Itachi kills Juzō, but it is revealed Juzō switched places with a water clone and attacks Yagura, who transforms into Version 2 mode and attacks Juzō with a Tailed Beast Ball. Juzō blocks it with his Kubikiribōchō, but is impaled when the blade breaks in half. Itachi subconsciously defends himself by using Amaterasu on Yagura, who is left seriously injured. As Juzō dies, he orders Itachi to flee to escape from capture. At the Akatsuki's hideout, Itachi is assigned a new partner, Kisame Hoshigaki.

Sasori, Itachi, and Kisame pay a visit to Deidara to recruit him on Pain's orders. Deidara is recruited into Akatsuki, partnered with Sasori, and the two are ordered to kill Orochimaru, who escaped into the Land of Wind. Itachi and Kisame are given a mission in Kusagakure. Kakuzu asks about a replacement partner, Pain tells him to wait. Sasori collects intel on Orochimaru left to him by Kabuto Yakushi. As they approach Orochimaru's hideout, Orochimaru's snakes detect them, and inform Orochimaru. Sasori orders Deidara to keep an eye from the sky so Orochimaru can't get away. Sasori brings out his Third Kazekage puppet, while Orochimaru reveals a reincarnated Third Kazekage in his possession. The two fight. One of the attacks from the reincarnated Third Kazekage damages Deidara's clay bird, causing him to retaliate. The Third Kazekage manages to free himself from Orochimaru's control, returning to the Pure Land. Sasori seizes the opportunity to attack, but Orochimaru retreats into his hideout. Deidara explodes it. On a gathering, Sasori informs Pain that Orochimaru is likely alive, as they were unable to find his corpse. Itachi fills them in about the Impure Reincarnation Technique. Akatsuki receives a mission from the Land of Hot Water, to kill an apparent immortal. Kakuzu, Itachi, and Konan are sent on the mission. Konan goes in as a decoy, and as Hidan prepares to attack her, Itachi and Kakuzu reveal themselves. Hidan and Kakuzu fight. Kakuzu is impressed by Hidan's immortality, and Hidan manages to destroy one of Kakuzu's hearts. Hidan is recruited into Akatsuki and partnered with Kakuzu. Akatsuki learns about the recently founded Otogakure, and plans to check it out, suspecting Orochimaru's involvement in it. They also learn of the joint effort with Sunagakure to destroy Konohagakure, and of the Third Hokage's death. Itachi volunteers to evaluate the situation, covertly wondering about Sasuke's safety.

Itachi and Kisame sneak into Konoha and Itachi is surprised of how much Sasuke has grown. As they attempt to kidnap Naruto, Sasuke confronts Itachi and orders everyone to stay away, as he is the only person who will kill Itachi. Itachi tells Kisame that Sasuke is his younger brother, much to Kisame's surprise. However, when Sasuke tries attacking him with Chidori, Itachi easily disarms him, breaking his wrist and brutally beating him. Despite feeling guilty for what he has done to Sasuke, Itachi uses Tsukuyomi on Sasuke to make him relive their parents' murder for 24 hours in order to make the latter's hatred increase before fleeing. Years later, Itachi encounters Naruto, whom he asks why he is obsessed with saving Sasuke. Naruto replies he considers Sasuke to be a brother surprising Itachi, who then asks him what would he do if Sasuke attacked the village and Naruto says he will protect the village and stop Sasuke without killing him. This convinces Itachi to put his trust in Naruto. When Itachi and Sasuke had their final battle, Itachi succumbed to his illness and poked Sasuke on the forehead one last time before dying. After being reanimated and stopping Kabuto with Sasuke's help, Itachi told Sasuke he didn't need forgiveness and he would always love Sasuke no matter what path he took before Itachi's soul returned to the afterlife.

Episodes