Hey man :],
err here's what I brainstormed:
- English/Jap teaching
- Diplomat
- Journalism
- Photography
- Music?
- Travel industry
- Japanese product distributor: music, books, movies, food
(I'm sorry

)
I think journalism is your best bet, since it covers a broad range of material. You need to write well though : /
If you're looking for short-term jobs,
http://www.boobooski.com can help you with setting up an internship to japanese winter/summer resorts.
*I'm thinking of doing it next year >_<
Good luck with your decision : D