In reply to crazydaisy:
There's lots and that link covers most of it. Don't think it mentions Jogasaki which is a day trip from Tokyo. Best place I went to was Ogawayama (sport, trad and bouldering) but that is a weekend trip and summer only.
There are usually a few foreign climbers living in Tokyo so try and track them down (at one of the walls, used to meet at T wall in Edogawabashi?). Maybe easier to find your way around with them if you don't speak Japanese.