Kabuto Yakushi

is a character in the anime and manga series Naruto.

Kabuto is the last part of the Japanese name for aconite, a plant which can either alleviate pain or kill, an apt description for his character. Additionally, a kabuto is also the name for a samurai's helmet or headplate. With his former teammates, Yoroi ("armor") and Tsurugi ("sword"), they form an armor-helmet-sword trio. Kabuto can also refer to a rhinoceros beetle. His family name, Yakushi, is the Japanese name of the Medicine Buddha, Bhaisajyaguru.

Background
Kabuto Yakushi is a character whose origins are largely unknown. As a young boy, Kabuto was found amongst the enemy dead after the Battle of Kikyo Pass by a chief medical officer of the Konoha Medical Unit Squad. The officer brought Kabuto with him back to Konoha, raised him as a son, and taught him medical jutsu when he got older. At some point in time, Kabuto was recruited by Sasori of Akatsuki, who sent Kabuto to spy on Orochimaru by using various jutsus to transform him into a sleeper agent. Orochimaru discovered this, and released Sasori's jutsu over Kabuto's memories, leaving Kabuto with the option to follow him. With a little persuasion, Kabuto agreed to side with Orochimaru. In part II, it is unknown why he does not wear a Sound headband.

Kabuto has assumed the position of Orochimaru's personal medic, assistant, and general right-hand man. He also serves as a spy for Orochimaru, playing the role of Sasori's servant to gain knowledge of Akatsuki's plans. Through his affiliation with Konoha, Kabuto was also able to acquire the rank of Genin and enter the biannual Chunin Exams, using the first few phases of the exam to gather information on his fellow participants for Orochimaru's use. Additionally, with the medical expertise taught to him by his adoptive father, Kabuto is able to carry out human experiments for Orochimaru, while at the same time increasing his own knowledge of the human body.

Search for Tsunade
With Orochimaru being heavily injured as a result of the failed invasion, Kabuto accompanies him in searching for Tsunade, who they hope will be able to heal him. Upon finding and in time seeming to persuade Tsunade, Kabuto notices that Tsunade's healing jutsu is filled with killing intent, and as such stops her before she can kill Orochimaru. With it clear that Tsunade won't willingly help them, Kabuto and Orochimaru lead Tsunade out to another battlefield in the fields with Kabuto aware that the other Sannin Jiraiya is nearby after learning of this during his failed attempt to assassinate Tsunade's assistant Shizune at Orochimaru's request. Kabuto then fights Tsunade in the hopes that he can force her into submission. After taking a soldier pill to boost his abilities, Kabuto is able to keep up with Tsunade and land a number of disabling attacks, though she eventually lands a crippling attack upon him. Upon recovering, Kabuto slits his wrists, drenching Tsunade in his blood and invoking her hemophobia, allowing him to land a series of unopposed attacks.

When the reinforcements for Tsunade arrive, Kabuto is pitted against Shizune, who he quickly defeats. As he returns his attention to Tsunade, Naruto Uzumaki also comes to her rescue, surprised that Kabuto is a spy for Orochimaru. While Kabuto doesn't view Naruto as much of a threat, Naruto is able to hit Kabuto with his Rasengan, doing so much damage to Kabuto that the latter is unable to fully heal. While Kabuto had managed to strike a fatal blow to Naruto's heart before the Spiraling Sphere hit him, Tsunade heals Naruto before he can die, leaving Kabuto to lie on the ground, defeated. Once Orochimaru is defeated, Kabuto escapes with his master.

Sasuke Retrieval
As Orochimaru anxiously awaits Sasuke Uchiha's arrival at their lair, Kabuto encourages him to switch to a new body while he still can, even offering his own body. Although Orochimaru rejects the offer, Kabuto finds a strong body for Orochimaru to switch to just in case. Although Kabuto's efforts seem to have been needless for a while, Orochimaru finally grows tired of waiting for Sasuke and switches to the body that Kabuto prepared. Later when Sasuke finally arrives, he sees how rude he's being to Orochimaru. He tells asks him not to be as rude even though Orochimaru's appearance has changed it's still Orochimaru. Sasuke then response with a glare and Kabuto seems to sense the power of Sasuke's chakra and backs off.

Sasuke and Sai
When Team 7 comes to meet one of Sasori's agents, Kabuto is revealed to be that agent. Yamato, disguised as Sasori, is able to learn some things from Kabuto, though just as he is about to capture the latter Orochimaru shows up. Although it seems as though Orochimaru is about to kill Kabuto as a traitor, Kabuto cuts off the Sasori disguise's head, having intended to kill the actual Sasori under Orochimaru's orders. With his cover blown, Yamato calls to the rest of his team for assistance, and Naruto eventually starts to fight Orochimaru. At the start of the battle, Kabuto tries to attack Naruto, though he is almost instantly repelled by one of Naruto's roars.

After the battle, Kabuto joins Orochimaru and former Team 7 member Sai in returning to their hideout, and Kabuto is tasked with leaving behind a dead body that looks like Sai to prevent anyone from following them. On the way to the hideout, Kabuto remains suspicious of the actual Sai, though his suspicions are seemingly lifted when the pursuing members of Team 7 apprehend and restrain Sai. Thinking Sai to be an ally, Kabuto frees Sai so that they can join efforts in defeating Team 7, though Sai turns on Kabuto and restrains him. Unable to escape, Kabuto is forthcoming with information, and discourages Naruto from trying to retrieve the traitorous Sasuke. Kabuto is left by himself as Team 7 searches the lair, though is at some point freed and joins Orochimaru and Sasuke when they depart.

Hunt for Uchiha
After the conclusion of the Team 10 arc, Kabuto is seen attending to a bedridden Orochimaru. Kabuto exits the room to retrieve some new medicine for him just before Sasuke breaks in and attacks Orochimaru. When Sasuke emerges from Orochimaru's room after having defeated him, Kabuto bears witness to a "recording" seen through Sasuke's eyes of Sasuke's conscious pushing Orochimaru out of his body. Before Sasuke leaves, Kabuto states to him that he will eventually come to exact revenge for Orochimaru on Sasuke, then go after Naruto. Kabuto then integrates Orochimaru's remains into his own body, which then begin to take him over; this is in an attempt to feel alive in and of himself, as he had defined himself entirely as Orochimaru's deputy, and now needs to find a new cause.

Kabuto eventually takes his data book on Akatsuki's members and, confronting the combined Team Kakashi and Team 8 (with Yamato in for the pregnant Kurenai), he reveals his attempt to integrate Orochimaru's remains into himself, which have steadily continued to consume his body; Hinata observes through her Byakugan techinque that the remains have subsumed about 30% of Kabuto's body, to include one of his eyes, giving Kabuto Orochimaru's powers. Kabuto chats with the group for a moment about his reasons for the integration before turning over the data book to Yamato. He then escapes Yamato's attempt to apprehend him and vanishes. His current whereabouts are unknown.

Abilities
Kabuto is a talented ninja, particularly because of his medicinal abilities displaying ablities that not even Tsunade were aware of. Kabuto has been said to be equal to Kakashi Hatake in ability on more than one occasion, and has likewise been shown to be able to kill ANBU members with relative ease. With his extensive knowledge of the human body, Kabuto has the unique ability to be able to reactivate dead cells and grow new ones, as well as being able to keep test subjects alive for much longer than is feasible. During his battle with Tsunade, she remarks that Kabuto's senses referring to his jutsu quickness and fighting ability might surpass her own in her prime.

Quotes

 * "You've thrown it all away! Dreams don't come true when you're dead!" (To Naruto)
 * "Orochimaru-sama"
 * "Hehehe... You can't beat me. You have no skills, unlike Sasuke. (To Naruto)
 * "If this kid learns how to control his chakra, he'll be unstoppable." (About Naruto)