Children's Book- Magic involved

[jaecheondaesong]

I can't remember too much detail except that magic was involved and it was centered around children, at least 3. One of the antagonist was a man who got caught up in the magic (he may have been trying to steal or exploit) and ended up getting the face of a rat which he later attempted to correct using plastic surgery. However, this is all i can remember, which is unhelpful i know.. :(