Random boy?

An orange haired boy kidnaped and forced to become the sacrifice for there dark lord Shi no gurippu but the unexpected happened they took everyone doing the ritual consuming them and then fusing part of himself with that of the boys soul. After waking up he went home confused why he woke up in a room full of blood with no one there when home he rung the police and reported the room a couple weeks since then he noticed horns growing out of his head. he wonders the world now with horns on he's head, voice in his brain cursed to be that of part demon and next heir to the title and throne of the Lord of death