Maps of Japanese Warlords - Complete and detailed maps of Japan in the Warring States period, all the provinces, warlords' domains, locations of battles, and so on.
Old Maps of Japan - Index of antique historical and political maps of Japan.
Regions and Cities - Japan Information Network maps of various regions in prefectures.
University of Texas Libraries - Japan Maps - Country, city and thematic maps from the Perry-Castañeda Library Map Collection, along with links to maps on other web sites.