I would say that the Japanese and American/European games markets are quite different. It may be difficult to write essentialy Japanese games for the Japanese... the industry also may not be inclusive to non-Japanese for these reasons, and others dealing with cultural differences.
However, that said... you have a unique opportunity at your age to study the language and see if you enjoy that, (you wont get far as a game developer in Japan without a firm grasp of the language and its idoms and eccentricities), from there you can visit the country, maybe even attend language school there (something I would again definitely recomend for anyone interested in doing business in Japan, if that is possible or not---), and from there you may have other plans or desires or opportunities that arrise for you.
I would try to find if there are any American game developers in Japan, I don't think so, the markets are quite different, and the Japanese work environment is quite different. But that doesn't mean you shouldn't take advantage of the time you'll have to spend studying the language and culture.