Okay. I'm on my way out the door, but here are a few high-traffic fandoms from anime/manga:
Bleach, D. Gray-man, Tsubasa Reservoir Chronicle, Ouran High School Host Club, Naruto, Prince of Tennis
Domestic cartoons:
Avatar: the last Airbender, Batman (The Animated Series, or Beyond)
Game fandoms: Final Fantasy (specify number, VII is probably the most popular)
Those are just the ones I'm most aware of, of course. A swing through ff.net to check who's got high numbers might be a useful tactic for this kind of thing.
Any of these combined with a quirky inanimate object will likely get some response.
Thanks for paying attention; it just gets to me to feel invisible to an organization whose aims I support, you know? And I have a hard time promoting OTW to anime/manga fans when there's no point of entry or commonality I can point to. It's like the "pan-fandom" archives all over again. And using the 'free prompts' to stand in for Everyone Else feels a whole lot like "take on the burden of educating us about who you are!"