There was one I used to go to all the time near Kashiwa, which is a ways from downtown tokyo, but if there is one around they are always fun to wander through. It definately is not the same there now than it was 10 years ago. Tuned cars were literally everywhere when I was walking around. Most noteably were the skylines and older two door STI's. There was also a number of GTR only shops as well as Z only car lots that I visited that had some old Z31 300ZR's. If you have time, try to visit tokyo tower and go to the top. Makes for a great view of the city and just fun to hang out around that area.