While there may be loads of cool t-shirts in every shop in Japan, nothing is more satisfying than making original Hokusai t-shirts that only you will own and no one else. At a printmaking workshop, Kume.JP offers small workshops for practically no money (6000JPY or $50 USD for two people). Check out some of their work on their Facebook page. You can book a reservation here: http://www.japanican.com/en/tour/detail/ACT1S001B I highly recommend it. It’s pretty quick, high quality, very few people do it, and they make great gifts.
The owner sets everything up but will help you with every step. The experience is fun and you get to sip on some local tea while waiting for your final product to be packaged. In addition you get a printed history of the place and the directions on how to screen print as a keepsake.