[spicytuna]

As far as I understand, each high school has an entrance exam which is done in Japanese. If you can go there and reach a grade 10 Japanese equivalent within a year, I'll personally pay for your tuition fees.

But more importantly, what kind of visa will you be using?

Your best bet would be to get a working holiday visa. You won't be able to extend it but you'll be able to live and work in Japan for a year.