As if discovering that things like jikininki and vampires existing wasn't enough, Tristan learns that there's many more "other" in the world than he could even imagine. In the third book, Moon Child, Tristan's newest ally and friend, Mamoru, tells him quite a lot about the seven shinwa, though the information isn't close to complete. While the names of each genus might not be Japanese in origin, it's said that the actual creatures themselves, in some form or another, are Japanese. Sadly, Mamoru doesn't know how these races have come about. Most don't.