[Hatredcopter]

If you go through a proper exchange program, you'll be placed with a Japanese family to live with, which is much more culturally rewarding (and cheaper). In Japan, you need a guarantor to rent an apartment. A guarantor is a Japanese national who signs your rental contract, as an added bit of security for the landlord.

As MMM said... you really need to go through an exchange program, or else try for an international school. A foreign minor who can't speak Japanese and doesn't live in Japan trying to enroll in a Japanese high school is just not feasible...