Just use your own bank card from a major US bank at ATMs, they dispense cash extremely close to spot rate, compared to converting at a currency exchange place.

In Tokyo, hit up harajuku and omotesando for awesome fashion. I'm really curious how well those boutiques have survived (around the world hasn't been pretty over the last year).

but aside from that, Tokyo is a day trip for me, the real cosmopolitan action is in Osaka.