[kenmei]

Look for international schools. Most have 1 year programs that are specifically for foreigners trying to learn japanese. Specifically i know Kanda international school has this. If you wanna go beyond that and do a 4 year college program, look into Ritsumeikan Asia Pacific University (not the Ritsumeikan in Kyoto, it's in Beppu). Up to you, both you have to show that you/your parents have enough money to support you thru the school year I believe.

good luck