Kimimaru is a character of the Naruto Series. He was a member of the Kaguya clan, the last surviving member after his clan's disastrous assault on Kirigakure, in which all but him were wiped out.
Kimimaro was born into the Kaguya clan three years before the start of the series. He was born as a rare holder of his clan's kekkei genkai, Shikotsumyaku, and his clan, despite their battle-lovingness and bloodthirstyness, grew to fear him, keeping him locked up for most of his young life, releasing him only to fight for the clan when needed. When the Kaguya clan moved to strike the village of Kirigakure, Kimimaro was released from his prison cell and sent to kill as many people as he could. During the attack, Kimimaro's Shikotsumyaku abilities allowed him to easily kill many shinobi and, at dawn, he saw he was the only survivor of the Kaguya clan, all his clansmen having been killed due to underestimating their opponent's defenses. As he wandered aimlessly, he was found by Orochimaru, one of the legendary Sannin, who took Kimimaro under his wing and made him into one of his most powerful followers. Under Orochimaru, Kimimaro found and brought a young man named Jugo to Orochimaru, promising the latter that maybe Orochimaru could do something about Jugo's uncontrolable, murderous tenancies and forming a close friendship with him. He also became Orochimaru's desired host body for his Living Corpse Reincarnation. Growing up proud to be Orochimaru's desired host body, Kimimaro was given the Cursed Seal of Earth, which Orochimaru gave to all his strongest followers in similar fashions. Afterwards, Kimimaro fought and defeated Orochimaru's bodyguards, the Sound Four, in unison and forced them to accept him as their new leader. As he continued to serve Orochimaru, Kimimaro fell ill with an unknown disease and was placed into the most intense medical care that Kabuto, Orochimaru's right-hand man, could give him to keep him alive for as long as possible.
Kimimaro made his debut in part 1 of the series where Kabuto Yakushi awoke him out of his medically-induced slumber and told him of Orochimaru's suffering at that point and asked him what he thought his purpose was since he was no longer a use to Orochimaru as a host body. Kimimaro decided that his purpose then was to ensure Orochimaru's continued existence and to bring him the body of Sasuke Uchiha, his replacement, as a way to prove his loyalty to Orochimaru and, in his eyes, give his "worthless" existence some "value". As he left to go and find Sasuke, he visited his friend Jugo and assured him that Sasuke was his replacement and thanked him for their friendship before proceeding to find Tayuya, one of his former teammates. Once he had, he took the coffin that contained Sasuke's body and told Tayuya to kill Naruto Uzumaki and Shikamaru Nara, before leaving with the coffin. Once he reached an open meadow, Kimimaro was caught up to by Naruto, whom Kimimaro proceeded to battle. Naruto created hundreds of shadow clones with his Nine-Tails chakra, however, Kimimaro created a bone sword with his Shikotsumyaku kekkei genkai and used his Dance of the Camellia to counter Naruto, dispersing all of his shadow clones, and allowing Sasuke to free himself from the coffin and leave after waking up.
As he was about to kill Naruto, Kimimaro was kicked away by Rock Lee, who proceeded to battle Kimimaro in Naruto's stead, allowing him to pursue Sasuke. Kimimaro saw Lee as a strong opponent, but managed to easily dodge his attacks at first due to their linear form. After Lee drank some Sake by accident and began to utilize the Drunken Fist, Kimimaro was unable to keep up with his unorthodox movements as was stuck down and disarmed of his sword. Impressed, Kimimaro activated the first stage of his Cursed Seal of Earth and used his Dance of the Larch technique to protrude bone spikes from his body that allowed him to cut Lee's face, sobering him up and struck him down. He then easily caught Lee's kick with his bones when the latter attempted to use his Front Lotus technique and nearly killed him, but the two were separated by Gaara via the latter's sand. Seeing Gaara there so suddeny surprised Kimimaro, but he attacked the latter using his Ten-Finger Drilling Bullets technique, but Gaara's automatic Shield of Sand blocked it, and Gaara noted that Kimimaro was hasty.
Kimimaro saw Gaara as a stronger opponent than Lee, his sand being a strong defense. Recognizing Gaara as a long-range fighter since he would be difficult to get close to, Kimimaro began to evade Gaara's attacks and pointed out that since his techniques and defense both involved using sand, Gaara was foolish to fight where there was not sand. Gaara then drew Kimimaro's eyes to the sky above and caught him by the feet with his sand, saying that as long as he had his sand, he could use it to create more. Kimimaro was then trapped and crushed by Gaara's sand, but survived by creating a shell of bone under his flesh. Kimimaro then fully activated the first stage of his Cursed Seal and broke out of Gaara's sand, saying he wouldn't underestimate him again. He was then shocked and unable to counter as Gaara created a tsunami of sand and buried him with it and then attempted to crush him again. Kimimaro survived somehow and proceeded to release the second stage of his Cursed Seal and pulled himself out of the sand.
Kimimaro proceeded to strike Gaara and repel him, but failed to hurt him due to the latter's Armor of Sand. Kimimaro, determined not to underestimate Gaara further, utilized his two part Dance of the Clematis to trap Gaara and allow him to kill him with a powerful bone drill. But Gaara countered with his ultimate sand defense, which shattered the drill. After Kimimaro told Gaara of his faith that he would live on through Orochimaru after he died, Gaara mocked his faith in Orochimaru and burried Kimimaro 200 meters in the ground. However, he used his Dance of the Seedling Fern to attack from below and emerged from within the one of the bone spikes, enraged at Gaara's mockery of him. Kimimaro then tried to attack Gaara, but died of his fatal disease midway.
In part 2, Kimimaro was revived, along with many other very powerful ninja by Kabuto Yakushi as a military weapon. Teamed up with others like Hanzo and Chiyo, Kimimaro engaged the samarai in the Allied Shinobi Forces alliance and killed many, able to fight at the best of his ability with his disease no longer effecting him, while also showing that he still retained his loyalty to Orochimaru. He encountered Naruto Uzumaki again and remarked that he needed only to look at Naruto to see that time had truly passed upon witnessing his mastery of Kurama, the Nine-Tails,' power, before dodging Naruto Rasenshuriken attack. Continuing to fight, Kimimaro suddenly began to feel the effect of the Impure World Reincarnation's release and was sent back into the afterlife after his soul broke from its shell.
Kimimaro was not truly a violent person, despite his herritage as a Kaguya, and only fought because his clan needed him too, which being needed was always something he wanted. After he met Orochimaru, Kimimaro became extremely loyal to him and became one of his most powerful followers. His loyalty to Orochimaru was so high that he was proud when Orochimaru wanted him for his host body and began to see that as his purpose in life. He was later saddened when he fell ill and became useless as a vessel and cried at losing that ability. Other than surprise, Kimimaro showed no emotion at all other than disgust until Gaara insulted his faith in Orochimaru, which caused him to become enraged just before his death. Kimimaro also had a habit of underestimating more powerful opponents, as he underestimated Gaara multiple time during their fight, nearly dying each time. He also seemed to have a somewhat pompous attitude and had verbal disrespect for his opponents. Despite this, however, Kimimaro had a sense of honor as he allowed Rock Lee to take his medicine and stopped his attack midway at his request.
Kimimaro was an extremely powerful shinobi, so much that he defeated the Sound Four, Orochimaru's personally picked bodyguards, by himself while barely using the power of his Cursed Seal of Earth. He, even when in a dying state, was able to prove himself a deadly opponent to the likes of Naruto Uzumaki, Rock Lee, and even Gaara, fighting all three of them one after the other without a break and without ever actually being defeated by any of them, which showed Kimimaro had amazing stamina. He also had great speed, agility, and strength, enough to easily dodge Gaara's high-speed sand attacks at fairly close range and pull himself free from Gaara's Sand Binding Coffin after enhancing his physical power with his Cursed Seal, a feat that no one else before him had done or since him has done. Kimimaro also had tremendous determination, able to force his dying body to move and fight and battle, which should have been impossible.
Kimimaro's main source of power was his kekkei genkai, Shikotsumyaku, which only he held out of his generation his clan, and his Cursed Seal of Earth. The former allowed him to manipulate his osteoblast and osteoclast cells, allowing him to manipulate his skeletal structure as a weapon and forms new bones at will. It allowed him to pull, fire, or protrude steel-hard bone weapons from his body as offensive moves against his opponent or defensive moves for himself and the latter allowed him to make use of a Sage Mode-like power that greatly enhanced his strength in its first stage or a transformation similar to Sage Mode that was a second shape that resembled a dinosaur in its second stage. Using these two things together, Kimimaro managed to overcome an immensely powerful opponent like Gaara, albeit at the cost of having great difficulty. His Shikotsumyaku also made him very deadly at close-range combat and he formed many swift "dances" that combined his Shikotsumyaku with taijutsu to dealy effects, able to destroy hundreds of Kurama-enhanced shadow clones of Naruto without even being touched himself and overcome Rock Lee, a formidable taijutsu fighter.