[Sangetsu]

You can also try Maruzen in Marunouchi (right across the street from Tokyo station). This store has the largest selection of foreign language books I've found in Tokyo

The next best place to try is the Book Off store in Meguro. It is within walking distance of Meguro station, and it is where I buy most of my books. The B1 level is make up almost entirely of foreign language books, and the prices are dirt cheap. It is also a good place to find cds, dvds, and video game software.