Natsume Yuujinchou has moments of this, as well, with Natsume agreeing to be a vessel for some pretty weird gods/demons.Requirements:
1) Must be at least a main character, if not the protagonist, that is, er, 'house-sharing'.
2) The body or the mind (or both) must be shared between the human and the non-human. So it's possible that the mind is shared but the body is not, or that the body is shared but the mind is not, or that both are shared. It's all fine, as long as something is shared.
3) They cannot be the same entity or the same kind of entity, though. So no werewolves or ghost possessions or similar things - there have to be two distinct entities from different species/groups, so no humans that turn non-human or humans sharing minds/bodies with other humans (or ghosts of humans). The human must be sharing his or her body or consciousness with a separate non-human. They have to be different people, and at least one of them isn't (and never was) human.
4) Must NOT be hentai or ecchi.
5) Any other genre is ok.
Fire away! And thanks!
