I like to visit Ikuo san at SO BOOKS in Yoyogi Hachiman. I could spend hours looking through the super excellent collection of rare and collectible books on art, photography, design, fashion and culture. He has an especially cool selection of 1970's & 80's Japanese street photography books. There are even a few books on ashtanga yoga behind the counter, if you ask he can show you.
on the web:
shop : http://www.book-oga.com/
blog : http://sobook.blog9.fc2.com/