is there a home stay system my friends could sign up for for japan?

The first and most important thing your friends have to do is not worrying about place to stay in Japan but worrying about visa to come to Japan.

Yes, it's called a sharehouse. You can usually find them in Tokyo. Basicly it's a *** house with at least six rooms. Where people share the house and live togather, The rent I think you pay once a month, but all in all it's a really great place to stay for forigners. My friends and I are actually planing to rent one once we go to JApan

Try Japan Foundation, they have trips to Japan, to homestay and to learn about the culture of Japan.

I stayed with a Japanese woman in Tokyo and enjoyed it very much! I contacted her through the home stay web.

www.homestayweb.com

A hotel...