Kimimaro

was the fifth member of the Sound Four, thus temporarily changing their group name to the Sound Five. The original four were forced to accept him as their leader against their will, as Kimimaro's combat abilities far exceeded all of their skills combined.

Background
Kimimaro was the sole survivor of the Kaguya clan, who were battle-loving barbarians. Being a rare owner of the kekkei genkai, Shikotsumyaku, Kimimaro's father, fearing his son's abilities, locked him up in a cage for most of his life, releasing him only when he was needed to fight for the clan. The Kaguya clan was wiped out when they attacked Kirigakure, seemingly for no reason other than the desire to kill. Having underestimated their opponent's defenses, they were slaughtered, with only Kimimaro surviving.

With nowhere to go, Kimimaro was eventually found by Orochimaru, and was recruited as one of his most loyal ninja. While belonging to a clan that loved killing, murder, and slaughter, and being the most powerful of this clan, Kimimaro was not truly violent, because he never really knew the outside world. Thus, the only reason he fought was because his clan needed him to do so, and being needed by someone was the one thing he truly desired. However, when he met Orochimaru, his desires changed to serve him, and to ensure the continuation of his master's dreams and ambitions. Kimimaro was selected to be one of Orochimaru's next bodies, primarily because of the rare Kekkei Genkai he possessed. However, Kimimaro was unfortunately afflicted by an unknown disease, and hence, was no longer useful to Orochimaru.

Kimimaro was a close friend of Jūgo, one of Orochimaru's test subjects, and was the only person capable of suppressing Jūgo's killing instincts. After hearing that Kimimaro had died in Part I to ensure Sasuke Uchiha reached Orochimaru, Jūgo believed that Kimimaro's spirit continued to live on in Sasuke, which was why he joined Taka in Part II.

Personality
Kimimaro had a strong devotion towards Orochimaru, bordering on religious zealotry, or considering him a father figure (the manga suggesting the former, and the anime suggesting the latter), as Orochimaru was the only person to seemingly care for and inspire him. On his way to Kirigakure, he encountered Zabuza Momochi and Haku, apparently shortly after they met each other. Kimimaro's relationship with Orochimaru was similar to Haku's relationship with Zabuza, both having similar backgrounds, and both found a purpose in living for their respective master. His dedication to Orochimaru was so great, that, despite his body's failing strength, he was able to will himself into battle, and still proved himself as an extremely dangerous opponent for the likes of Naruto Uzumaki, Rock Lee and Gaara.

Kimimaro demonstrated extreme distaste for "trash" ninja, as he put it. He generally attempted to "clean it up", by killing the people who were "trash", even if they were his allies (he plotted to kill Tayuya after she defeated Shikamaru, because she was unable to deliver Sasuke by sunset). Despite his verbal disrespect of his opponents, Kimimaro had been shown to have a sense of honor in battle, as demonstrated when he stopped the battle to allow Rock Lee to take his "medicine".

Despite being born into the battle-loving Kaguya clan, and being the strongest member due to his unique abilities, Kimimaro is not truly violent, as he is locked up in a cage for most of his life. Instead, he is a quiet and calm individual, and only fought in the war against Kirigakure due to his desire to be useful.

The most notable trait that separated him from his four colleagues was that he rarely showed emotions, other than surprise, until Gaara insulted his faith in Orochimaru, causing him to become enraged before his death. It was also shown that Kimimaro was crying silently when he discovered he was no longer useful to Orochimaru.

Appearance
Kimimaro was characterized by his pale skin, vivid green eyes, masculine facial features, and shoulder-length white hair, which he wore divided down the middle on his head (distinguished by an atypical 'zig-zag' hair parting) with two separate partings on either side of his face. As a child, Kimimaro wore his hair longer, tied in a loose pony-tail near the middle of his back, though the initial style was very similar to his current one.

Under the wing of Orochimaru, Kimimaro wore a specialized version of the traditional Sound-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.

Apparently, as a user of the Shikotsumyaku abilities, Kimimaro was given a different bodily structure from others, as Kabuto Yakushi claimed that there had been too little information on his body to give any medical treatment for his terminal illness.

Chūnin Exam arc
In the anime, Kimimaro was revealed to have participated in many of Orochimaru's schemes. He was seen to be be responsible for killing Shiore and her companions (Orochimaru would later impersonate Shiore during the second part of the exam). At this point, he gave a bloody cough, but decided to ignore it. When Orochimaru betrayed and killed the Fourth Kazekage and his bodyguards, Kimimaro was noted to have given contribution to make this assassination successful. At this point, he finally succumbed to his fatal illness, that in turn would have Kabuto placing him in intense medical care to keep him alive for as long as possible.

Sasuke Retrieval arc
Under the manipulations of Kabuto, Kimimaro left Kabuto's care (even after his body was broken from illness, his will power moved his body) so that he could bring his replacement, Sasuke Uchiha, to Orochimaru, and prove his loyalty. Prior to leaving, Kimimaro went to see Jūgo one more time. Despite Jūgo's protest of Kimimaro's ill body, Kimimaro assured him that Sasuke is his successor, and he thanked Jūgo for their friendship.

He succeeded in taking the barrel Sasuke was in, but Naruto Uzumaki caught up with him to take Sasuke back. Kimimaro easily held off Naruto, until Sasuke could get away on his own. Rock Lee saved Naruto seconds before Kimimaro could kill him, allowing Naruto to go after Sasuke. Kimimaro proved more than a match for Lee, and it was only after Lee started using the Drunken Fist that he gained the upper hand, Kimimaro being unable to react to his sporadic movements.

When Lee started to sober up, allowing Kimimaro to attack him again, Gaara arrived, and saved him from Kimimaro. Though Gaara's sand attacks managed to hold off Kimimaro for a while, Kimimaro's second state of the Cursed Seal crushed all resistance. After Gaara insulted Kimimaro's loyalty to Orochimaru, the sand ninja used his ultimate attack, which essentially turned the whole battlefield into a plain of sand and buried Kimimaro deep beneath it. 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. Fueled by his hatred of being insulted, Kimimaro emerged from one of the bones, preparing to strike the two at point blank range. However, he finally succumbed to his illness just before he could kill Gaara, who was already out of chakra, and dies. Gaara later came to the conclusion that no-one can defeat loneliness, even if it means to care for an evil person like Orochimaru.

Abilities
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, the source of the Cursed Seal, he said he had not seen such control of the Cursed Seal since Kimimaro when commenting on Sasuke's control of the seal. Kimimaro also has a very strong determination, as when his failing body would be impossible to move physically, he forced it to through sheer will, and still proved to be a deadly opponent. 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.

Shikotsumyaku
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 combine his chakra with calcium, making his bones flexible. Kimimaro also stated that his bones were stronger than steel. Kimimaro used this ability to wield his bones as weapons in battle, and could use them in the forms of taijutsu attacks (which he called dances) to give him a variety of abilities.

Taijutsu
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 without breaking a sweat, at the same time not allowing himself to be struck. Kimimaro combines his Shikotsumyaku and taijutsu capabilities to form many deadly "dances".

Cursed Seal
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. When in his Level 2 form, his 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.

Trivia

 * Though some fans believe that his full name was Kimimaro Kaguya, the second databook only said his name as Kimimaro.
 * Most of Kimimaro's actions in the series, prior to his appearance in the Sasuke Retrieval arc, are exclusive to the anime.
 * is an ancient Japanese title of nobility. is Japanese slang for a person with thin or shaved eyebrows; this stems from a practice used by noblemen in ancient Japan where they shaved their eyebrows and painted two dots similar to Kimimaro.
 * Both Itachi Uchiha and Kimimaro died in battle due to illness. Incidentally, they are both important to Sasuke's development in life.
 * Kimimaro appeared in the omake at the end of Naruto Shippūden episode 129, like many of the other minor characters.

Quotes

 * "If I can't be of any use, then there's no reason for me to live."
 * "It's not brainwashing! Orochimaru-sama... is all my own reasoning!! What the hell would you know about it?!"
 * "I am not his pawn! He is the one, the only one who ever gave my life meaning! But how could the likes of you ever understand that!?"
 * "That's what Orochimaru-sama said to me that day, but... people are born for a reason... that's what I think... they have something they're meant to do with their lives... and I am no different... I was put on this earth to protect Orochimaru-sama and his ambitions."
 * (Talking about Sasuke) "This is the dream vessel... but you all were too late..."