Known Early Life
Kabuto's life is steeped in Mystery. The first Mention of him, he was found wounded at the batttle of Kikyo pass. He was taken in by a Konoha Medical-nin, who taught him everything he knew. Kakashi's first statement when he sees Kabuto in the hospital with an unconscious Sasuke at scalpel point was "Oh, you're that medic's son" , making Kakashi seem more knowledgeable about Kabuto than he had previously shown.
At some point, he was put under the mind control of Sasori of Akatsuki to spy on Orochimaru. Orochimaru discovered this and freed Kabuto from Sasori, seeing that Kabuto may have had some useful jutsu for him to take advantage of.
Sasori however, would never find out that his jutsu had been broken by Orochimaru, as he would be killed by Sakura and Chiyo and then tell them where to go to meet a spy that he was supposed to meet up with, only to be impersonated by Yamato, who had no idea what Kabuto knew about Sasori.
Somewhere along the line, Kabuto joined Orochimaru in Otogakure (the Village hidden in Sound) and became somewhat of Orochimaru's right hand man, and was always Orochimaru's first choice when sending someone on a spy mission, as Kabuto was one of the few people in the Naruto universe who's true thoughts were never revealed anywhere, not in battle, not in speech. It is implied that even Orochimaru doesn't know Kabuto's true allegiances, as when he tells Kabuto to go capture Sasuke, who was in the hospital, that now would be the only chance he would have to stop him, as though he were pndering what Kabuto would do next. Yakushi was next seen as a member of Konoha, attempting to beat the Chunnin Exams along with the "rookie nine", consisting of Naruto, Sasuke, Sakura, Ino, Choji, Shikamaru, and Shino, Kiba, and Hinata. This was supposedly his 7th time in attempting to pass the exams.
His first mention and appearance in the series, he is seemingly quite a nerdy kid. Upon hearing Naruto Uzumaki proclaim to the rest of the aspiring chuunin in the room that he would one day beat every one of them, he was forced to react to stop him from getting hurt, possibly as another way to force them into thinking he was their friend. Talking to them like a cocky superior, he asked them if they needed any help with the specifics as this had been his seventh time apparently in taking the exams. They were astonsihed to think that he was actually taking this exam again after all of it had gone by, but he told them that it was harder than they thought. He asked anyone if they wanted information on any of the new ninja, and of course Sasuke was the very first to ask him about Rock Lee and Sabaku no Gaara, but he wondered how Kabuto would possibly know about them.
He pulled out a deck of cards that he infused with his own chakra, and told them that with these he was able to carefully analyze his enemies and collect information on them. He also commented that sasuke knowing their names made this a much easier process, and first went ahead and told him abotu the one from the village that they were familiar with, Rock Lee. Lee was a specialist in taijutsu, but nothing else and had gone on multiple C-Rank missions with his team of Guy, Ten Ten, and Neji Hyuuga.
Gaara, however, the mysterious ninja from sand was a different story, he had done multiple D-Rank missions, several C rank, and even one B-Rank mission with his team of Temari, Kankuro, and his sensei. Kabuto commented that there are very few genin that ever go on B missions, as often they're just simply far too tough for them. The thing that scared Kabuto the most though, and the others around him, was the condition that he had come out of all of these missions : unscathed. With this, Sasuke and Naruto felt slightly chilled, until kabuto quickly changed the subject, talking about how there was also a new village in the midst of their ranks, Otogakure, aka the Village Hidden in Sound. Kabuto stated that the three genin from there (Dosu, Kin, and Zaku) were simply just representatives of the no name backwater country of Sound.
Upon hearing this, the three became violent, and attacked Kabuto where he stood. He dodged the kunai thrown from one, and wehn one blow was thrown towards his face he was able to carefully but swiftly move out of the way, his glasses broken. Looking at them, he wondered what had happened, in a slightly amused fashion, until he felt sick and began to vomit. The sound ninja bandaged up told him the secret to this, the amplifier on his arm, the sound from it had been directed by Dosu's chakra into Kabuto's ears, and thus disrupting the flow of some of the water and causing him to lose his balance and just go nausious. Kabuto picked up his glasses, and simply walked away after being told by the three patriotic genin that they would be the "next big thing" and that he would be killed if he got in their way again.
Little did the genin know, Kabuto was more in on their plan than they werem as compared to their relationships with Orochimaru, Kabuto was second to none. It was unrevealed what or how Kabuto did in the first part of the Chuunin exams, the written section, other than that he passed it, as he was able to assist Naurto and his friends in the Forest of Death, the second part of the exams. He had apparently strayed away from his team, which had already gotten their scrolls it would seem. Since he had no idea where they had been split up, apparently, he decided that he would help out Naruto and co. while they ran through the death filled woods on their way to the tower in the center of the forest with their scrolls. Along the way, Kabuto and Sakura noticed that they were going around in circles, as there had been the same branch pattern and rocks for the past few miles...it took the others a while to understand what this meant, but Kabuto knew what they were doing immediately : another genin was attemping to confuse them with genjutsu, to wear them out without fighting for their scrolls. A sly movement, if it weren't for them discovering what was going on due to Kabuto's smarts and the genin's miscalculations...they had thrown their kunai too early to try and take them down, and it was quickly stopped.
Naruto went out and called out their opponent, only to be warned by Kabuto that this was not a good idea, as there appeared to be a lot of them. In reality this was just another trick from the genjutsu using genin, and the multiple kunai were simply being thrown from one point in synchronization with his clones to make it seem as though there were many of them, from one point. Kabuto was about to tell them a plan to devise in order to make their strategy fall apart, when suddenly from out of the blue a kunai was thrown into his face, he was quick enough to dodge it, but it still scraped his face, and broke his glasses. It was in this moment that Kabuto's character went in depth, as his eye color changed to red, and he looked enraged with a passion. He has only mentioned this red eye technique once since this instance, only a few chapters later, saying that it was too dangerous for him to be a part of the third round of the chuunin exams with his red eyes. We still don't know if there was some truth in this statement, but for the most part Kabuto only left the exam to fulfill the orders of his true master...Orochimaru.
He met up with Orochimaru in an uninhabited area of the Leaf village at the moment, and discussed their plan. Sasuke was ill stricken in the hospital because of the curse mark set upon him by Orochimaru, and that now was the time to take him with them. Kabuto's mission was to kidnap the young boy and then bring him back for good. He also noted that if Kabuto was ever going to try and stop him, that the only way he could would be to kill Sasuke now, meaning that Orochimaru didn't even know what side the young boy was truly on. Kabuto froze for a moment at these words and looked at him with a very strange look in his eyes, only to tell him that he would never betray him. Upon arriving at the hospital he murdered all of the Anbu Stationed out side of Sasuke's hospital room, who was still quite fast asleep from the effects of the attempted curse mark seal from the elite jonin Kakashi, also his master. Finally, after all of the Anbu were actually dead, he came up to Sasuke, with a scalpel at his unconscious throat, ready to clip the tube that was over his mouth. Right when he was about to take him (or so we assume, he may have been trying to kill him and stop Orochimaru, or just do something else altogether, we still don't know his true motives) , he was suddenly stopped by Kakashi. Kabuto commented that maybe next time they may want to leave about ten anbu as opposed to six, as it was far to simple to kill them. Kakashi began fighting Kabuto in hand to hand combat, but it turned out that what Kakashi was fighting was an animated Anbu corpse made to look like Kabuto, using one of Kabuto's signature techniques it would seem, the Art of Dead Souls. In actuality the real Kabuto had been postering as one of the many dead Anbu on the ground, and when given the chance and Kakashi realized that he was just a shadow clone, Kabuto leapt out of the window, revealing the face under the anbu mas to be his.
The Search for Tsunade
Kabuto accompanied Orochimaru to ask for Tsunade's help, at which they gave her a few days to decide. When the meeting between Tsunade and Orochimaru took place,
Kabuto was sent to kill anyone who'd interfere, but got scared and left when he saw Jiraiya. He then stopped Tsunade and Orochimaru, being a medical ninja he saw that Tsunade's technique was fatal, not healing. He decided to retreat to a more opened location to fight her, and she followed.
The two fought and Tsunade started to gain the upper hand, to which point Kabuto used his trump card... knowing her phobia of blood, he cut himself. Before he could kill her however, Jiraiya, Naruto, and Shizune appeared. He fought with Shizune and Naruto and was winning, but Naruto hit him with the Rasengan which put him down.
During a ruined assassination attempt by Orochimaru and Kabuto to kill Sasori, Kabuto was faced by Yamato and Sakura while Orochimaru fought the 4-tailed Naruto. Knowing that Orochimaru didn't want them dead because of their usefulness, Kabuto decided to heal Sakura who was struck violently by the out of control Naruto.
After Sasuke absorbed Orochimaru, Kabuto would later meet with Naruto and co. to give them all of the information gathered on Akatsuki and it's members, he then revealed that he used his medical skills to graft portions of Orochimaru's body onto himself. When explaining why, he compared himself to Naruto and Orochimaru to the Kyuubi within Naruto. Kabuto said that he was always dependent on Orochimaru's power but he's going to make Orochimaru's power his own... he later claimed that Orochimaru's trying to take over and he's trying to resist. Before he left, he stated that he will seek revenge on Sasuke.
Kabuto is later seen in the Waterfall village attacking Waterfall ninjas, he has also left behind corpses for the Leaf village to find which baffles Anko. He then finds Tobi's hideout and confronts Tobi. Since Kabuto worked as a double agent against Akatsuki, Tobi accuses him of being a traitor and attacks but Kabuto keeps his distance, using Resurrection to the Impure World to summon: Deidara, Itachi, Kakuzu, Nagato, and Sasori.
Rather than attack, Kabuto insisted that he wants to join Tobi. Tobi was weary, wondering why Kabuto wanted to join him, Kabuto said that in return for providing soldiers for Tobi's war that he wants Sasuke. Tobi initially refused, but Kabuto resurrection someone that Tobi couldn't say no to, so Tobi agreed on the condition that Kabuto can't have Sasuke until after the war and he'll be supervising Sasuke at all times. Meanwhile, Anko and her group were following the trail of dead bodies Kabuto left right to Tobi's hideout and decided to report back to the Leaf village right away.
Tobi then reappears with a new mask and clothes, and once again wields his war fan. Kabuto mentions that the eyes he got from Nagato are nice, but Tobi says they were his to begin with. Zetsu interrupts revealing that they got Kisame's info, to which Tobi states that it's time to go after the Kyuubi. Kabuto suggests that he foes to get the Hachibi and Kyuubi.
Tobi wonders what Kabuto's trying to do, but Kabuto insists that it's his way of earning Tobi's trust... but wants to be compensated with Hashirama's tissue, but will settle for a Zetsu. Tobi agrees to give Kabuto one Zetsu if he succeeds. Tobi then wanted to show Kabuto something. They go deeper into Tobi's lair which reveals a massive plant growing all through it, and Tobi reveals that it was grown using tissue that he stole from Hashirama. He then reveals vast legion of Zetsu clones. Kabuto then departs with Deidara on one of Deidara's flying clay creations.
Kabuto and Deidara closed in on the island turtle that Naruto and Killer Bee are on, but is intercepted by Onoki whom ambushed Kabuto and punches a hole in Kabuto's chest, but it's Deidara's clay clone which explodes. However it wasn't the real Onoki either, it was a rock clone made by Akatsuchi, and they were accompanied by Kurotsuchi. While they're engaged, Kabuto reveals that he has made a bigger, more powerful clone of Manda which finds and attacks the island turtle. Deidara detonated some of his clay bombs beneath the island turtle trying to make it topple over, but it didn't. Kabuto went off to find Naruto and Killer Bee while Deidara kept the others busy, but Kurotsuchi chased after Kabuto. Kurotsuchi used Congealing Caustic Blast but it missed, then Aoba, Yamato, and Motoi arrived and Kurotsuchi told them to capture Kabuto as she sends him their way with Water Trumpet, that too misses but it made Congealing Caustic Blast that was on the ground expand and snare Kabuto in a cement-like material, she then covered Kabuto in more.
Yamato created a wood board for Aoba to go over and read Kabuto's mind without getting stuck himself, but Kabuto leaped out of his own skin, revealing himself as a hideous giant snake, and escaped after he swallowed Yamato whole and unsummons Deidara. He then presents Yamato to Tobi and saying that since capturing Naruto and Killer Bee was impossible, he captured Yamato to augment Zetsu, and Tobi told him to get to work. After strengthening the Zetsu clones, Kabuto revealed more Edo Tensei summonings: Han, Utakata, Yugito, Fuu, Yagura, Roushi, 3rd Raikage, 4th Kazekage, 2nd Tsuchikage, Hazashi, Dan, Asuma, Hanzo, Chiyo, Kimimaro, Haku, Zabuza, Shin, Chuukichi, Pakura, and Gari. Tobi asked if Kabuto could handle it, Kabuto said that it'll be difficult to control so many but he can do it. Kabuto ordered them to set out, but after leaving Tobi's lair he spotted and attacked Anko whom was spying on them.
Tobi saw Anko's unconscious body with Kabuto and started accusing Kabuto of trying to get him and the alliance to kill each other, and demanded that he kill Anko. Kabuto refused, saying that he needed her alive. Tobi made him an ultimatum, to show Kabuto's loyalty he had to reveal the secrets of Impure World Resurrection to him. Kabuto hesitantly complied,so Tobi brought forth Fu and Torune to use.
Kabuto later revealed that he has also brought back the previous Seven Swordsmen along with Zabuza; Fuguki, Mangetsu, Jinin, Ameyuri, Jinpachi, and Kushimaru. To make things worse for the alliance, Kabuto later revealed the 2nd Mizukage as well as Kinkaku and Ginkaku.
When Itachi and Nagato crossed paths with Naruto and Bee, Kabuto decided to capture them in order to have more leverage against Tobi. This didn't go as planned and Itachi was coincidentally freed from Kabuto's control, in the mean time Kabuto decided to unveil his bargaining chip to the alliance that he used against Tobi... Madara Uchiha. While Kabuto was having his fun, Itachi and Sasuke confront him, Itachi wanting to stop Edo Tensei and Sasuke wanting to talk to Itachi. Kabuto tried to enlist Sasuke's help against Itachi, calling him a common foe, but Sasuke saw things differently. The two brothers attacked Kabuto, but he proved too tricky and revealed a few surprises such as attaining Karin's healing ability and Suigetsu's liquifying ability, but also that he had ventured to Ryuchidou and learned Sage Mode. He started the fight using White Violent which created a bright explosion which momentarily blinded and deafened the brothers and Kabuto went to abduct Sasuke but was faltered by Itachi. Itachi decided to use a forbidden Uchiha clan jutsu, Izanami, to get Kabuto to undo Edo Tensei, but it takes a while to use once prepped. The brothers then counter attacked in unison, but their efforts failed. Itachi decided the only way to defeat Kabuto would be to use a one-time only jutsu, Izanami, which would decide fate at the cost of the user's eye. Kabuto pressed the brothers with another powerful attack, Inorganic Transmigration, making the cave itself come to life and impale Itachi with stalactites; Itachi survives thanks to being one of Kabuto's unkillable zombies, but Sasuke used Amaterasu to stop Kabuto from re-taking control of Itachi. During this fight, Itachi tried to appeal to Kabuto, causing him to recollect his past which led him to this point. Kabuto begins his attacks again, showing the bodies of those whose power he took for himself appear out of his torso. He used the Sound 5's abilities to subdue the brothers and then used Orochimaru's ability to try and absorb Sasuke, but the brothers helped each other and managed to stop Kabuto, until Kabuto sliced Itachi in half and was about to put a new control seal in Itachi, but Sasuke managed to stop him. At this point Izanami takes effect and Itachi loses the vision in one of his eyes as a cost, and Kabuto's placed in a genjutsu loop which he must figure out how to end.
Kabuto is enshrouded in mystery. He is also extremely unique in the way that he fights, using techniques that are not only unique to him but also very tactical and innovative for a shinobi.
"Chakra Scalpel" where he creates an aura of chakra around his hand that can cut like a blade.
"Dead Soul" where he can temporarily control the recently deceased.
"Mystical Hand" where he can heal the wounds of others and himself.
"Secret Healing Injury" where he focuses his chakra to heal himself from the inside- out. And
"Temple of Nirvana," an illusion technique that induces sleep in his opponents.
"Mole Hiding" where he's able to swiftly travel underground.
Now that he has integrated Orochimaru into himself and further augmentation, he has displayed:
"Snake Authority Spell" where gigantic snakes emerge from his body to attack or bind the opponent.
"Many Hidden Shadow Snakes" where a dozen snakes emerge from his body to attack or bind the opponent.
"Resurrection to the Impure World" in which Kabuto sacrifices the living to resurrect the dead as his servants.
"Chakra Draining Seal" is able to drain away a person's chakra that is inside the seal's placement.
"Snake Summoning" is able to summon huge snakes to obey his bidding.
"Snake Form" Kabuto is able to shed his skin and become a large snake with arms and legs, appearing similar to a dragon.
"Uzumaki Healing Chakra" which allows him to rapidly heal himself.
"Hydrification" which allows him to convert his body into liquid and back again.
"Sage Mode" where he harnesses natural energy to greatly augment all of his abilities and gives him great sensing abilities.
"White Violent" where he spits a dragon which explodes, creating a blinding light along with bone wrenching sonic vibrations.
"Inorganic Transmigration" which allows Kabuto to bring inanimate things to life and control them.