I'm not sure if you've left yet....but, you're going to Tokyo, where everything is photographical! Grab a suica card, load it with Yen and hop on the seiko JR line. It takes you through the heart of Tokyo. Get off at every stop! I was there last October, here are some shots. (almost) Each set is a stop on the line.
Shibuya, Ueno, Shinjuku and Harajuku (this infamous girls come out on Sundays) are great for people watching. Find some Temples and have a blast!