Yikes! Could it be any more complicated?
This handy mini map is available for free at post offices in Japan (Japan Post). It measures about 23 x 10 cm (9″ x 4″). Available only in Japanese and includes all train lines and stations for Tokyo Metropolitan Area for 2010, including Saitama, Chiba and Kanagawa prefectures.
If you need a scanned original, you can download it here as a PDF file.
