...my definition of vampire is loose. I mean youkai that eats humans or consumes something human. Both rumia and patch talk about eating humans in the game don't they?
A youkai is a pretty well-defined thing in Japanese mythology (see
here). They don't have anything to do with vampires, for one who originate in eastern European mythology, and two only drink human blood. Youkai can outright consume humans.
As for the species of "<profession> youkai", like Patchouli and Alice (and possibly soon-to-be Marisa and Reimu), they're normal humans whose powers have grown so much they've gone pretty much beyond being human. This ties into the whole Youkai definition: things that've lived long enough or gained enough power to become "something else, something more than they were". But these youkai aren't ones who consume humans, probably since they are/were one themselves. So they're different.
By the way, it was Meiling (standard youkai) that talked about eating the protagonist, not Patchouli (witch youkai).
