Jimbocho is the designated "book town" of Japan. Home to several publishing houses and shops selling used books, unusual books and rare collectors find. Journey to the book town starts at the Jimbocho subway station, where the subway walls is appropriately decorated with stacks of books.
I have seen a Tokyo Eye show on NHK world about Jimbocho and I absolutely loved it! Even though I don't read Japanese I will definitely buy a bunch of used Japanese books when I get there.