Just wanted to say that from what I know, you can be in Japan for 90 days without any type of visa. This is for AMERICAN's. Every country has different permissions.
If you stay longer you must have a student or work visa.
I also have a questions for you guys:
If you were going to school part time, would you get a job for the rest of your day while in another country?
Would it conflict with study or would you really need the money? I suppose it might be hard to find a job if you didn't speak Japanese. I don't know though, I haven't done this.
I would love to find a job AFTER my schooling was done or if school was really good then I would just go longer.