Musō (monk)

Muso is the sixth detachment of Naraku, but unlike the others detachments he was given Onigumo's heart. Making him the first known detachment that has his own heart. He first appears as a human, albeit, nude, male with shoulder length unkempt hair. His most striking feature was his lack of a face. After acquiring the face of a handsome priest, he takes his robe as well, shortly before stealing a samurai's armor. Muso does not follow Naraku's will and acts own his own free will.

Histroy
Muso is created when Naraku digards a collection of mutated flesh from his arm into a chasm where it slithers off. Later the flesh stops before a gang of criminal samurai, where it is promptly impaled on sight. Soon afterwards a hand erupts from the mutated flesh grabing the sword before fully emerging from the mutated flesh. He appears to be a man, but he has no face. He slaughters the entire gang and rips off their faces, to use one as his own. He is disappointed by all of the samurai's faces finding each of them unattractive, so throws the faces into a river nearby.

However, his luck would change when an priest appears before him to banish him. He finds the priest's face to be handsome so he decides to take it. He kills the priest and steals his face to use as his own. He also takes the priest robes before he departs. Later he kills another samurai, steals his armor, and his horse. He goes on a murderous spree; destroying villages and robbing valuables. Despite finding enjoyment in his deeds he is also frustrated. He feels empty inside, as if something is missing. Before he dwell on his thoughts any futher he is confronted by InuYasha's group(minus Kagome). InuYasha questions him about being one of Naraku's detachments, but he simply replies that he has never heard of Naraku. The half demon dog questions him further by asking his identity, but once again he cannot answer InuYasha because he cannot recall his name. He decides to name himself Muso after the priest whose face he stole. An impatient Inuyasha attacks him managing to slices off one of Muso's arms, however a swarm of Naraku's poisonous insects appear conjoining together at what is left of Muso's arm, regenerating it completely. InuYasha renews his attack, but this time Muso fights back with a transformed arm not unlike that of Naraku's. Soon Kagome appears before the group having returned from her own time. As Muso catches sight of Kagome, an image of Kikyo flashes in his mind. He quickly grabs Kagome thinking that she is Kikyo becuase of their identical appearance to each other. InuYasha frees her then uses the Wind Scar to dispatch Muso.

Awakened Memories
However, Muso's body begins to regenerate in a different area, he vows revenge against InuYasha. He eventually stumbles on a cave that he vaguely remembers. He decides to go into the cave, while there his memories return to him. Muso is really the bandit Onigumo in an new body. As he runs out of the cave he runs into Kagome and Kaede were going to check out the cave. When he attemps to abduct Kagome again, Inuyasha interferes once more. He remarks that he remembers InuYasha now, and then recalls the events that hapened 50 years ago. After his body transformed and Naraku was born, he left the cave to test his new body, but he was not in control of his new body. He remebers how Naraku killed Kikyo and how she choose to follow InuYasha in death instead of using the Shikon no Tama to save her. After Kikyo's body was burned along with the jewel Onigumo's conscious was supressed by Naraku, he recalls the experience as being imprisoned in a dark place. The next thing he remembers is that he was a lump of flesh and was born again.

Muso asks InuYasha why he still alive as he remember that Kikyo sealed InuYasha to a tree. He and InuYasha begin to fight once again, however Muso having learned how to control his new body better fares much better then last time. Muso can transform his body into weapons and can regenerate his body. InuYasha uses the Wind Scar multiply times only to have Muso regenerate from the damage. Muso begins to press his advantage while InuYasha is slowly tiring. Miroku realizes that the key to Muso's regeneration is the spider mark, which he predicts is the spot where Muso's heart resides. Fortunately for Muso that Kagura saves his heart by knocking it out of the way of InuYasha's Wind Scar. The poisonous insects take Muso's body away.

Meeting Naraku
The posinous insects take Muso to nearby forest where Naraku is waiting. For the first time ever Naraku and Onigumo come face to face with each other. In the manga Muso instantly attacks Naraku and is absorbed almost imeditally. The anime goes into further detail with the encounter. Naraku tells Muso that Kikyo is alive again and she is as he remebers her. Before he can question Naraku about Kikyo InuYasha and Miroku appear. As InuYasha starts a fight with Naraku, Muso runs away. Still angry at Naraku for his imprisonment he decides to go back to kill Naraku. He stabs Naraku in chest however doing this allows Naraku to reabsorb him. Naraku reveals that he still needed Onigumo's heart as a connector for his body, which why he needed to reabsorb him.

Abilities
Shapeshifting - Muso is able to transform any part of his body, commonly in the form of tendrils to wrap, constrict and pierce targets.

Transformation - Muso demonstrates the ability to take on a semi insectoid form, which grants him a prehensile tail with a stinger at the tip

Regeneration - Muso is able regenerate his entire body so long as his heart is intact. He can regenerate from mere pieces in a matter of moments.

Facial theft - Having been created without a face, Muso can take on facial identities of others by apply faces to his head after ripping them off.

Trivia

 * Muso's faceless depiction seems to contribute to Onigumo's severely crippled condition as his body was coated with bandages with only one eye and his mouth being visible, thus leaving his undamaged face a mystery.