Mangekuo

Team Kakashi, also known as Team 7, is a team led by Kakashi Hatake, which was formed after the members became Genin. The members were selected in order to balance out their talents: Naruto, the worst student in his graduating class, would benefit from Sakura's intelligence and Sasuke's proficiency with ninja skills. Sakura would similarly benefit from her more battle-capable team-mates, whereas Sasuke would benefit from being forced to work with others.

It was later revealed that Kakashi was chosen specifically to be the leader of Team 7, because of Naruto and Sasuke. Kakashi's duty, in addition to training the team, was also to keep the Nine-Tailed Demon Fox in Naruto contained, and to keep Sasuke from walking down a dark path, since they had similar traits that would allow Kakashi to better understand him.

When Sasuke defected from Konoha at the end of Part I, Team 7 was disbanded for the next two and a half years. The remaining members reformed as Team Kakashi at the start of Part II in order to go and rescue Gaara. After that mission was completed, Sai was added to the team as Sasuke's replacement under Danzō Shimura's suggestion, and Yamato briefly led the team when Kakashi was hospitalized. Although intended to be a temporary replacement, all of Team Kakashi's subsequent missions have been led by Yamato. According to Sakura, Team Kakashi also has the best teamwork with Team 10. The Yamato-led Team Kakashi, otherwise known as "Team Yamato", was later part of the Eight Man Squad led by a recovered Kakashi.

For the first half of Part II, the remaining members of Team 7 tried their best to bring Sasuke back to Konoha. They first track him to one of Orochimaru's bases, but he escapes. Later, with the help of Team 8, they try to intercept him in his search for Itachi, but they lose his trail. After this failure, Sasuke affiliates himself with Akatsuki and becomes an international criminal. Konoha decides to break ties with Sasuke because of this and Sakura and Kakashi separately attempt to kill him to prevent him from implicating the village in any of his future crimes. When Sasuke does not hesitate to try and kill them both during the first reunion of the original Team 7 since his defection, Naruto also concludes that Sasuke must be stopped. However, he insists that only he can fight Sasuke

Itachi was born into the Uchiha clan 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 Great Shinobi World War, which emotionally traumatized him and turned him into a pacifist. 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, hence neglecting his youngest son, Sasuke. However, during this time Itachi showed great affection towards his little brother and even encouraged his father to come to the Academy enrollment 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.
A young Itachi with his family. From left to right: Fugaku, Sasuke, Mikoto, Itachi.AlienGamerAdded by AlienGamer
When the Uchiha 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. 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.
Before the fateful night arrived, Itachi discovered the existence of Madara Uchiha, who was attempting to rekindle the flames of war in Konoha. In return for not attacking Konoha, Itachi offered to help Madara claim vengeance against the Uchiha for turning their backs on him decades earlier; Madara agreed. Itachi slaughtered his entire clan overnight, sparing only Sasuke as Sasuke's life was worth more than the village to Itachi, and he could not follow through with the orders to kill him as well. Instead, he made himself out as a villain, who had killed their innocent family only to test his abilities. By doing so, he wanted Sasuke to take vengeance on him and become a hero to Konoha, thus redeeming the Uchiha name. He tortured Sasuke with his Mangekyō Sharingan and encouraged him to become strong enough to kill him and avenge their family. Hoping that his beloved little brother would someday be powerful enough to kill him, Itachi left the village as a traitor. According to Madara Uchiha, Itachi also had a lover, whom he killed during the Uchiha clan massacre.[4]
Itachi massacres the entire Uchiha clan.Magatama90Added by Magatama90 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 him 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 organization, along with Madara Uchiha, in case either ever acted against Konoha, all the while planning for his death at Sasuke's hands. While 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 organization. He was partnered with Kisame Hoshigaki, who he initially greeted with threats after the latter tried to intimidate him. Eventually, they became good partners for sharing a 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 his genjutsu, to which Deidara swore vengeance against Itachi.
At some time, Itachi contracted a fatal illness, to which he kept himself alive through the intake of various medicines, in the hopes of living long enough to die by Sasuke's hands.

One day when they were younger, Sasuke accompanied Itachi on one of his training sessions. Impressed by Itachi's skills, Sasuke asked Itachi to teach him something, but Itachi, as always, refused by poking him on the forehead and promising to help him later. As they returned home, Sasuke marveled at the Uchiha clan's accomplishments as explained to him by Itachi. When they encountered their father, Fugaku, he spoke to Itachi about an approaching mission. Itachi refused to take part, wishing to take part in Sasuke's Academy orientation. Seeing that Itachi was determined, Fugaku volunteered to go in his place.

Ever since his first appearance, Itachi had always been mysterious, and had 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 Sasuke.

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 did not possess any arrogance, and fully justified any statements he made about his power, even complimenting his opponents at times on their abilities.
In addition to being an extremely powerful ninja, Itachi had equally impressive intelligence, and was shown to be very wise. 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 realized the truth. 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 organization and its members, seeming to put the organization's success and secrecy before everything else. As such, 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.

After Killer Bee refused to train Naruto, Motoi guided Naruto and Yamato to the Falls of Truth, the place where Bee trained to control the Eight-Tailed Giant Ox. He instructed Naruto to sit on a platform and close his eyes. Soon after, Dark Naruto (闇ナルト, Yami Naruto) appeared, berating Naruto for how quickly the people from Konoha changed their ideals of Naruto and had started sucking up to him, which sickened Dark Naruto.Dark Naruto said that he was the manifestation of hatred that existed within Naruto's heart, the Nine-Tails liked him better, and exclaimed that he was the real Naruto and that Naruto was an impostor.They started to fight, but after a while, Naruto realized that they both had the same techniques, skills, and tactics. As a result, their fight was a draw and Naruto mentioned that if they continued like this, it would take a long time to settle it, so he awoke and told Yamato and Motoi what happened. Motoi told him that he must defeat Dark Naruto in order to learn how to control the Nine-Tails.
He appeared once again after Naruto returned to the Falls of Truth. Instead of fighting, Naruto projected an image from his mind of his autograph signature he was unable to give to the Konoha shinobi. This angered Dark Naruto, pointing out to Naruto that those people were part of the same villagers who treated him as an outcast and how much he suffered because of them, telling him shouldn't trust them. However, Naruto stated that he trusts the villagers because they are important to him. But what was also important was that he needed to have faith in himself, so he would have the strength to live up to the villagers' trust in him. Naruto's statement started to weaken Dark Naruto, forcing him to ask what was the reason for his existence then. Naruto stated that Dark Naruto was really him and thanked Dark Naruto for pushing him to be the person he was now. He hugged Dark Naruto when the latter tried to attack him, telling Dark Naruto that it was all going to be alright. Letting go of his own anger at their past, Dark Naruto's eyes lightened and he gave into Naruto's words, disappearing into Naruto.
Later, when Naruto entered his subconscious, the Nine-Tails expressed surprise as it could no longer sense any hatred within Naruto, and questioned Naruto about where the "real him" was, to which Naruto replied that the real him was right in front of it.