Speaking of modeling... If you're a foreign student on a scholarship here for an extended period of time, get a part time work permit (it takes a week after applying iirc) and join a modelling agency.
If you're lucky, you'll get gigs that pay 100k for a day, if you're less lucky, like me, there's still a chance for 10k yen for a few hours of work.
During my scholarship year I joined one agency with a friend thinking "why the hell not, it's really cheap". Despite being able to work only on weekends because of my classes, I got 2 gigs - one payed 10k for 2 hours of work, the other 10k for about half of a day, but some of the offers that came in, like a short Canon ad, were in the 100k range for a day.
It's also a great way to meet new people and "celebrities" (I met some of the AKB girls and they are really nice in person).
As for the agencies, I used
Free Wave and I guess I can recommend it, but I haven't heard anything about the others.