I went to Takushoku University's Japanese Language Program. Most of the students were from China or Taiwan. The only other caucasians in my class were a brother and sister team from Spain, so all of us only had Japanese as our common language. It really helped more with the development of linguistic ability than if my classmates had been, like me, from the States.
Oh, another thing. DO NOT let your family send you tapes of American TV shows. You will watch them instead of Japanese TV (I know I did) and miss out on opportunities to improve your skills.
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