The type of fan who's intrested in only ONE character (usually because they find them attractive) and hate the rest of the characters in the same work/franchise.
-Hey, who's your favorite character in this game? John? Thomas? Alice?
-Idgaf about neither of them, I'm only here for Nolan, he's like the only person I actually enjoy watching -Ah, so you're oni-fan then
A word typicaly used in Japanesse animes by younger female anime girls to their older brother or just by anoying weeaboos who think they know the whole damn language.