mudwerks:

A-Yokai-A-Day: Onryo | MatthewMeyer.net

There’s some confusion as to how to define yokai and bakemono in Japanese folklore, which one is a subset of the other, and whether or not yurei — ghosts — fit into either category or exist on their own. There doesn’t seem to be a clear definition of either term, but from my understanding of them I think that “yokai” is a pretty encompassing term that collectivizes all supernatural beings in folklore, Japanese and non-Japanese alike. Whether bakemono are a subset of that or just a related term, I don’t know, but I definitely think that yurei and their kin (like onryo and zashiki-warashi) fit in as a type of yokai, rather than stand alone.