how to know if a girl watches anime without asking?

C'mon, is it really that hard to ask a girl such a simple question? Have some guts! Assuming you're interested in this girl, asking in person will make you appear much cooler and more confident.

A good question to ask would be "do you know what anime is?" If she says yes, score for you. If she says "no, what's that?" you have a chance to explain yourself (give examples like "movies like Spirited Away, etc") and you can even recommend her some animes. It's a win-win situation.

I guess the second best way to find out if someone watches anime without asking them directly *ahem chicken* would be to ask her friends. For example, if you have a friend who happens to be friends with the girl, you can just say "I'm just curious", then ask if the girl watches it. I mean... if you wanna get really stalker-ish, you could check her facebook and see if she's liked any anime/manga-related facebook pages, maybe see if she posts any pictures or statuses that are anime-related, etc.

But man, just ask her. It's not like your asking her out, you're just asking her if she watches anime.

Hm... I guess you could ask her if she would rather live in a pirate, wizard, ninja, or shinigami world and why. You could mention that in these worlds she and other people could have these super powers or that it doesn't have to be set in the modern world. (If she asks those two questions, then she probably does watch anime.) Then see if her reasoning sounds similar to One Piece, Fairy Tail, Naruto, or Bleach. If she doesn't know what a shinigami is, then there is a good chance that she doesn't watch anime.

However, if she isn't into those types of animes you could "forget" what a reverse harem is and ask her if she knows what it means. Or you could ask her what genre it is when a girl befriends a group of guys and sometimes it ends up in a love triangle. She may not remember either, but you could encourage her by saying you only "remember" the reverse part. Just say somebody asked you and it's bothering you because you should know the answer.