Kimimaro was the only survivor of the Kaguya clan, a family of battle-loving barbarians. Being a rare possessor of the clan's Shikotsumyaku kekkei genkai, the clan patriarch feared Kimimaro's abilities and had him locked up in a cage unless needed for battle. The Kaguya clan was wiped out when they attacked Kirigakure, seemingly for no reason other than the desire to kill. Having underestimated their opponents' defences, they were slaughtered, with Kimimaro the sole survivor. Wandering soon after, Kimimaro was eventually found by Orochimaru, and recruited as one of his most loyal ninja.[2][3]

Kimimaro and Jūgo.
Under Orochimaru, Kimimaro found purpose in his life as he desired to ensure the continuation of his master's dreams and ambitions. Though Orochimaru took him under his wing to be one of his future hosts, Kimimaro did not mind such a fate if it meant being of aid to his master. Soon after, Kimimaro met Jūgo, a berserker whom Kimimaro felt a kindred spirit with. Kimimaro's friendship with Jūgo led to the events that resulted with him being branded by the cursed seal that Orochimaru developed from his research on Jūgo, whom Kimimaro talked into being experimented on in hopes that it would help him. With his new-found powers, Kimimaro defeated all four members of the Sound Four single-handed to be inducted into the renamed Sound Five. However, before his appearance in the storyline, Kimimaro became afflicted by an unknown disease that destroyed what remaining worth he was to Orochimaru. Kabuto Yakushi attempted to cure Kimimaro, but to no avail due to Kimimaro's unique structure and lack of medical information on his clan. Kimimaro was left bedridden to extend his wavering lifespan, unable to participate in the invasion of Konoha, which Kabuto claimed to be the factor that led to their defeat and retreat.

In the anime, it was shown that Kimimaro acted as a messenger to shinobi clans in the Land of Sound, order for them to swear loyalty to Orochimaru.[4]

Personality
Unlike the rest of his clan, Kimimaro didn't have a particular interest in fighting or killing and saw his abilities only as a means to be of use to others. He was a calm and quiet individual who would dedicate himself to whatever mission was at hand. As a child, he was more gentle despite his natural talent for combat and unique abilities which made him the strongest of his clan, as seen from him not wanting to hurt others he had no involvement with, and his interest in flowers. His gentleness is also reinforced by how empathetic and kind he was to Jūgo, being one of the few people able to keep Jūgo from losing control over himself.

After meeting Orochimaru, Kimimaro developed a strong devotion towards him, bordering on religious zeal or considering him a father figure (the manga suggesting the former, and the anime suggesting the latter), seeing Orochimaru's apparent kindness as a reason from him to exist under the notion that serving Orochimaru in anyway is the only purpose he has. Though Kimimaro's relationship with Orochimaru was similar to Haku's relationship with Zabuza, the only difference was that Orochimaru ultimately lost interest in him when he became of no use to him. Regardless, finding a new way to assert his existence, Kimimaro's dedication to Orochimaru was so great that he both willed his body to fight and proved to be an extremely dangerous opponent for the likes of Naruto Uzumaki, Rock Lee and Gaara. Gaara compared the eyes of Kimimaro to those of Sasuke Uchiha's, the eyes of those who only sought to prove their own existence, nothing more. Even after being reincarnated by Kabuto, Kimimaro retained his loyalty to Orochimaru and intended to carry out Kabuto's orders. Gaara commented on Kimimaro to be hasty and a extreme distaste for weak opponents, or "trash" ninja as he put it. As a result, he would kill any he considered "trash" ninja, regardless if they were friend or foe as was with the case of Tayuya for her group's failure to deliver Sasuke in time.

Despite his verbal disrespect of his opponents and over underestimating of their abilities, Kimimaro differs from his four colleagues in two ways: The first having a sense of honour in battle, as demonstrated when he halts to allow Rock Lee time to take his "medicine". Another difference is that he rarely showed any emotion other than surprise, except in moments relating to his ideals as seen when Gaara's insulting of his faith in Orochimaru caused him to become enraged before his death or when Kimimaro cried silently when he lost his usefulness to Orochimaru.

Appearance
Kimimaro was characterised by his pale skin, vivid green eyes, masculine facial features, two scarlet dots on his forehead which all the members of his clan possessed, and shoulder-length white hair, which he wore divided down the middle on his head (distinguished by an atypical 'zigzag' hair parting) with two separate partings on either side of his face. As a child, Kimimaro's hair is longer, which is tied in a loose pony-tail near the middle of his back, though the initial style was very similar to his later one.

Under the wing of Orochimaru, Kimimaro wore a specialised version of the traditional Oto-nin ensemble, consisting of a light lavender, loose-fitting, long-sleeved, zip-up shirt, black pants cut off around mid-calf, bandages wrapped around his ankles, traditional shinobi sandals, and a purple, rope-like belt tied in an inverted bow around his waist. He also wore two red, tube-like hair ornaments; one on either side of his head, securing two locks of his silvery-white hair. He did not wear a Sound headband, despite his extreme loyalty to Orochimaru. His Cursed Seal of Earth is applied at the base of his throat, where it is a circular pattern of three curved lines.

Abilities

Kimimaro using his Shikotsumyaku ability.
Kimimaro was referred to by Orochimaru as the most powerful member of the Kaguya clan, having "abilities that even his war-loving clan feared". Because of this, he was locked away in a cage for most of his life, only released occasionally when needed to fight other clans. His fighting abilities far outclassed all the members of the Sound Four combined, and his mastery of the Cursed Seal even impressed Jūgo, who is the source of the Cursed Seal.[5] In fact, Kimimaro is the only person before Sasuke who could control Jūgo without exerting any efforts. The fact that he could fight Naruto, Lee, and Gaara while dying of disease, and never actually being defeated by them, indicates he was an extremely powerful combatant at his peak. Indeed, even near death, his mere presence was enough to frighten the normally-arrogant Tayuya, as well as retaining a high level of stamina, which he showed in his battles with Naruto Uzumaki, Rock Lee, and Gaara, battling all three one after the other without collapsing.

In the anime, he could summon a wall of white smoke, which was powerful enough to push back several enemies.[6]

Shikotsumyaku

Kimimaro's Shikotsumyaku abilities infused with the Cursed Seal of Earth.
Kimimaro's abilities came from his kekkei genkai, Shikotsumyaku, which allowed the user to manipulate their own skeletal structure as a means of combat. Specifically, it allowed Kimimaro to manipulate his osteoblast and osteoclast cells, which are responsible for building or breaking down bone tissue. This ability gave him absolute control over the concentration of calcium within his bones, allowing him to control the density or malleability of them. Kimimaro also stated that his bones were stronger than tempered steel. Kimimaro used this ability to wield his bones as weapons in battle, and could use them in the form of taijutsu attacks (which he called dances) to give him a variety of abilities, as well as grant him a near-invincible defence, able to withstand most of the impact from even a chakra-enhanced blade, and cut through regular shuriken. He can also grow an entire forest of gigantic bone blades. Orochimaru has stated that this was the ultimate taijutsu ability, which is held in high regard, and the main reason why Orochimaru desired Kimimaro to be his next vessel.

However as a downside, a user of the Shikotsumyaku abilities, such as Kimimaro has a different bodily structure than others, as Kabuto Yakushi claimed that there had been too little information on his body to give any medical treatment for his terminal illness.[7]

Physical Prowess
Kimimaro's abilities made him well suited for close-range combat fighting, demonstrating tremendous taijutsu skills combined with equally impressive speed, agility, and dexterity. He was able to defeat several hundred of Naruto's Nine-Tails-enhanced shadow clones effortlessly, at the same time not allowing himself to be struck. Kimimaro combined his Shikotsumyaku and taijutsu capabilities to form many deadly "dances". Rock Lee, a taijutsu virtuoso, has claimed that nothing was wasted in Kimimaro's movement, and that he was a taijutsu master. Kimimaro also possessed immense strength, enough to pull himself out of Gaara's chakra-infused sand, which is normally difficult, if not impossible, due to its sturdiness.

Kimimaro also had a very strong determination and endurance, as when his failing body would be impossible to physically move, he managed to force it through sheer will, and still proved to be a deadly opponent.

Cursed Seal

The Cursed Seal of Earth.
Like many others of Orochimaru's closest followers, Kimimaro was given a cursed seal, which granted him tremendous power. He bore the Cursed Seal of Earth, which is said to be equal in power to the Cursed Seal of Heaven, and both Seals are said to be the strongest amongst the ones used by Orochimaru. When in his Level 2 form, Kimimaro's appearance was similar to that of a dinosaur, with dark grey skin, six large bone spines protruding out of his back, and a long bone-spiked tail. Jūgo stated that Kimimaro had great enough skill with the Cursed Seal that he could do a partial transformation. Furthermore, Kimimaro's fighting style changed after entering his Level 2 state; he became much slower, but his physical strength increased to the point of smashing through Gaara's sand defences with a simple tackle, and his skin became thicker and harder, making it impossible even for Gaara's sand to penetrate it.

Stats
Databook Ninjutsu Taijutsu Genjutsu Intelligence Strength Speed Stamina Hand seals Total
Second 4 5 3 3.5 3 4.5 4.5 3 30.5
Part I
Chūnin Exam Arc
In the anime, Kimimaro was revealed to have participated in many of Orochimaru's schemes. He was seen to be responsible for killing the Kusagakure ninja so that Orochimaru would impersonate Shiore. At this point, he gave a bloody cough, but decided to ignore it. However, while participating in the assassination of the Fourth Kazekage and his bodyguards so that Orochimaru and the Sound Four could impersonate them, Kimimaro's disease fully manifests. He is sent back to Otogakure to be placed by Kabuto in intense medical care to keep him alive for as long as possible. Hearing that his failing health has caused him to be of no use to Orochimaru, Kimimaro began silently crying for losing his purpose.

Sasuke Retrieval Arc
When the Sound Four took too long in bringing Sasuke to Otogakure, Kabuto decided to wake Kimimaro and manipulate him into aiding them even if meant he would die. Regardless as he forced himself out of bed, Kimimaro resolved that bringing his replacement, Sasuke Uchiha, is the only purpose he can do for Orochimaru. Prior to leaving, Kimimaro went to see Jūgo one more time. Despite Jūgo's protest for his health, Kimimaro assured him that Sasuke is his legacy while thanking Jūgo for their friendship.

Kimimaro vs. Naruto.
Arriving to find Tayuya and the casket holding Sasuke was in, Kimimaro threatened to kill her unless she kill some of the Konoha ninja, saying he only let her live because she had a duty to complete. He then left with the barrel, overpowering Naruto Uzumaki as Sasuke emerges from the coffin with Kimimaro covering his escape towards Otogakure. During the fight, revealing Orochimaru's intentions for Sasuke, Kimimaro was able to defeat Naruto when Rock Lee arrived and kicked him. Kimimaro saw Lee as a stronger opponent than Naruto.

Lee arrives to fight Kimimaro.
When Kimimaro chased after Naruto when he started to go after Sasuke, Lee caught his bone, allowing Naruto to leave. Kimimaro proved to be more than a match for Lee at first, but after Lee started using the Drunken Fist he gained the upper hand, Kimimaro being unable to react to his unusual movements even after he had figured out what Lee was using. After Lee managed to land an attack on him, Kimimaro admitted he couldn't read his movements. He then activated the first stage of his cursed seal to overpower Lee. He then used his bones to cut Lee's face and knock him down.

When Lee started to sober up, Kimimaro gained the upper hand again and struck Lee down. Believing he had killed Lee, he started to go after Naruto, but Lee stood up again in time. He caught Lee's kick with his bones and almost killed him. Gaara arrived at that moment, saved Lee, and began fighting Kimimaro instead. Kimimaro then retracted his bones as he acknowledged Gaara as a stronger opponent, his sand being a strong defence. He guessed Gaara wasn't a close combat fighter, recognising the difficulty of bringing Gaara to close range. When Gaara started to attack him, Kimimaro tried to use his Ten-Finger Drilling Bullets while dodging Gaara's attacks. Noting that all of Gaara's techniques involved sand, he pointed out it was foolish for Gaara to fight somewhere where there wasn't sand. Gaara brought Kimimaro's attention above to distract him while he caught hold of Kimimaro by his feet, and proceeded to explain that as long as he had his sand, he could use it to make more.

Kimimaro vs. Gaara.
Kimimaro was then trapped and crushed by Gaara's sand, but survived by creating a layer of bone under his skin. He then activated the first stage of the Cursed Seal of Earth and broke out. Kimimaro admitted that he had underestimated Gaara, but will not make the same mistake again. After surviving being buried by Gaara's tsunami of sand, Kimimaro tried to land a hit on Gaara, but his Armour of Sand blocked it. He then used his two-part dance to restrain and kill Gaara, but it couldn't break his ultimate defence.

Kimimaro's last seconds of life.
After Gaara insulted Kimimaro's loyalty to Orochimaru, Kimimaro begins to lose his focus before being buried two hundred metres below the ground, where the pressure can crush even steel. Kimimaro, however, used the last one of his dances to turn the battlefield into a forest of bones, that Gaara and Lee barely escaped by hanging onto a small cloud of sand, with the former's chakra reserves depleted. Fuelled by his hatred of hearing Orochimaru insulted, Kimimaro emerged from one of the bones and prepared to rip the two to shreds. However, he finally succumbed to his illness just before he could kill Gaara and died where he stood. Gaara later came to the conclusion that none can defeat loneliness, even if it means to care for a person like Orochimaru.

Part II
Shinobi World War Arc

Kimimaro is recruited as back-up.
In preparation for the Fourth Shinobi World War, Kimimaro is reincarnated by Kabuto Yakushi to fight against the Allied Shinobi Forces. After being mobilised, he becomes part of the group that Chūkichi requests assistance from, alongside Chiyo and Hanzō. He later encounters the remnants of the Surprise Attack Division with this improvised team, where Deidara is imprisoned. Pursuing the retreating opposition retreats, Kimimaro contemplated how Orochimaru's chakra, via Kabuto, now flows within him while having resolve to complete his assigned goals.

Kimimaro faces the Fifth Division.
When enemy reinforcements arrive from the Fifth Division to provide assistance, Kimimaro attacks them with his Shikotsumyaku, which manages to pierce even the samurai's chakra-infused blades. Fatally impaling several of these samurai by the following day, Kimimaro observes the arrival of Naruto's shadow clone, who notes that the outcome of this battle will be different than their last. Remarking that his appearance demonstrates that time had passed, he is then assaulted by Naruto's Wind Release: Rasenshuriken, though managed to jump out of it's range before being hit.

When Impure World Reincarnation was released, a shocked Kimimaro — who was still battling the Alliance's members — was enveloped in a light of sorts before his soul ascended from his deconstructing body to return to the afterlife.

Legacy

Kabuto producing a manifestation of Kimimaro's body from his navel-snake.
Kimimaro's words to him that Sasuke, who bore a curse seal like himself, is his living legacy inspired Jūgo to follow Sasuke by joining his group and following Sasuke's orders without question.

Though Kabuto Yakushi reincarnated Kimimaro for the Fourth Shinobi War, he also assimilated Kimimaro's DNA along with the rest of the Sound Five. By using Sakon and Ukon's kekkei genkai, Kabuto can manifest a construct of Kimimaro with access to his Shikotsumyaku kekkei genkai.[8]