As I red Chainsawman, It brought back memories from a manga I used to read like 12 years ago (it was “ongoing” at that time) about a kid/guy that, can’t remember the reason RN, had the soul/conscience of a wolf-like demon inside him. The drawing style was similar to “Übel Blatt”
He was searching for the relative of said demon (don’t know if it was brother or former friend) a black wolf-like creature.
Was pretty bloody if I remember correctly and the thing it had in common was, that his transformation looked pretty much like the wolf demon that Aki used (kon meme). His back would practically turn into the wolf head (same design, several eyes and stuff like that).
Don’t know is this rings a bell to anyone, first time posting about it.

Wolf-like Demon inside him sounded like Naruto for a second tbh lol. Otherwise the only things I can actually think of were
Wolf's Rain
Wolf Guy
Dance in the Vampire Bund
Jinrou e no Tensei

And although not related to any wolf-like thing but Übel Blatt reminded me of Bastard!! since the two occupy that same style in my mind.