[samurai007]

Many schools and teachers are happy to allow a JET to help out in things besides teaching English, especially if you can speak Japanese. Many high schools will have a drama club, and I bet the students would enjoy having the ALT help out with their plays, maybe take a role or help direct, etc.

In a larger town or city, there may also be theaters that perform plays. You might study Noh, or find a place that does western plays in Japanese.

Whatever your hobby, there is usually some way to pursue it, perhaps in new and unique ways, while in Japan.