I have a feeling that he’s a Tsuchigumo ~ a yokai spider boi.

omfg — “They appeared to people as having faces of an oni, a body of a tiger, arms and legs of a spide”

oni has those horns too :o

I agree. It could very well be a tsuchigumo. It's also very powerful yokai :)

I thought so as well. But the spiderweb on the cover can be hinted on that as well. And when he transformed even more so :3