Jigoku no Kuchi

Jigoku no Kuchi is a Dōjutsu of the Rinnegan used with the Naraka Path.

Usage
With the Naraka Path, the wounded user summons the King of Hell, who opens his mouth, pulls the opponent in with his tendril-like arms, and apparently chews through it. In fact, the opponent is deprived of some of his life force, which heals all injuries to the user. The now weakened opponent is then ejected from the mouth of the King of Hell.