Yomi

was a dark medical-nin who appears in the Naruto: Shippūden the Movie. He is a servant of Mōryō who comes from a long line of followers to Mōryō that have spent generations to perfect a dark form of medical ninjutsu.

Naruto: Shippūden the Movie
At the beginning of the movie he gives his men, The Gang of Four, special chakra-enhancement through infusing them with dark-chakra snakes; giving them access to jutsu they could normally not use. After his men took down the guards of Mōryō’s prison, Yomi then enters Mōryō's spirit cave frees him. He then offers his body as a spirit container for Mōryō until the can retrieve Mōryō's body. When Kusuna reports that Gitai was killed by Lee, Yomi doesn't care telling Kusuna to kill Neji, Lee, Sakura, and Naruto and then when the time is right to kill Shion. This results in Kusuna and the rest of the gang of four being killed. Shion then confronts Yomi and prepares to seal Mōryō. Yomi interferes however Mōryō wants to take matters in his own hands and bursts out of Yomi's body killing him. Yomi's body then fell in the lava when the volcano erupted. It is unknown if he survived or not, but his condition after Mōryō escaped from Yomi's body would suggest that he is no longer of any threat.

Abilities
Yomi has shown to have great expertise in medical ninjutsu. With ease, he can enhance the chakra of anyone he wishes, allowing to fight for longer periods of time and performed more powerful jutsu. His skill in medical ninjutsu were great enough to effectively (both only for a limited amount of time) use his body as a container for a demonic spirit.