Short courses in Tokyo

I would love to do a short course in Tokyo (1-4 weeks depending what is available) but all I find online are Japanese courses. It's not that I don't want to learn Japanese, I speak basic Japanese already, but I was hoping to find something interesting to do and learn something new in Japan. Perhaps language courses are the only short term courses available to foreigners in japan? If anyone have any tips and ideas, it would be appreciated. :)

What are you interested in? Language schools often offer those few weeks' intensive course, and for languages it makes sense to study intensively, I mean, several hours each day for a few weeks...