There are lots of places you could see. The Tokyo Metropolitan Museum of Photography sometimes has interesting exhibits:
http://syabi.com/e/contents/index.html and there are many smaller venues that can be found sometimes listed in the English language newspaper Japan Times, (Check them online) and other larger museums occasionally have photography exhibits. Japan Exposures
http://www.japanexposures.com/ should give you some ideas.
If you are looking for equipment, I'd suggest MAP cameras
http://www.mapcamera.com/ (in Japanese) in Shinjuku. They have both new and used equipment and at lower prices than the MacCamera shops like Yodabashi and Bic Camera. I a generally avoid them though they might be of interest. (I much prefer Yodabashi in Yokohama over the one in Akihabara and over any Bic Camera. Service is much better. English is available in Akihabara though, and may not be elsewhere).