Yomotsuhegui: Scions of the Underworld Vol. 1

Nawa Kanetsugu used to be a police officer, until his wife and child were murdered and he sought revenge by any means necessary. In a new quest for vengeance after he's released from prison, he discovers that a mortal wound won't kill him. A confrontation with a mysterious girl shows Nawa that he's eaten the fruit of Yomotsuhegui, the tree in the realm of the dead, and now he's an immortal with monstrous powers. The girl is a god of death who wants his help to fight other dangerous immortals, since there may still be a seed of justice in his heart. Will Nawa find his humanity again in saving others from supernatural evil, or will these ghastly powers turn him into a monster?