Waifu = wife. Unless you're a lesbian, it'd be a bit fucked up.
Otaku girls are usually fat or ugly. There was a nice bunch of them at my old HS. 2 of them were fucking hot with nice juicy tits and great asses, but the rest of them were textbook uggos. I mean really fucking ugly. If you get a hot one, good for you, but i wouldn't limit my options to just otaku girls.