One of the most famous places in Tokyo is the Kabuki-theater.
Exactly opposite (accross the street), there is a small knife shop selling japanese knives.
Also, I remember that there were two shops selling mostly american-made blades (at high prices of course) inside a shopping alley somewhere, but I cannot remember exactly where was that.
Maybe Copfish could help here.
P.S. Japan is a magnificent place. How I would like to be there again...