i live in nakano. walked a bit around shinjuku, harajuku, shibuya, daikanayama, ueno, and ginza. don't believe i've been to american blvd. yet. You should check it out. It's a little strip of denim/streetwear shops under that building heading away from the main drag through Shinjuku. Probably more expensive than Ueno prices for similar stuff, but since you were talking about leather I thought I'd mention it because there is a shop with lots of leather, belts and about a zillion buckles there.