Hakusan-jo Castle is a mountain castle said to have been built as a fortress by Takeda Nobuyoshi, founder of the Kai Genji and Takeda Clans. It also served an important role as the center of an information network of beacon towers, and as the front line of defense for Shinpu-jo Castle.
Hakusan-jo Castle Ruins are located in the area where the narrow space along the Kamanashi River meets the wide Kofu Basin. It sits atop Mount Nabeyama at an altitude of 570 meters between Shirasawa and Yahatasawa, with Mount Hattosan rising to a height of 882 meters behind it. The mountain ridge extends north and south as though to enclose the site, and a beacon tower marks the two ends of the ridge. The north beacon tower is located at an altitude of 602 meters, and the south Mukudai beacon tower at an altitude of 695 meters.
The two beacon towers and a number of other well-preserved buildings remain. In castle history, Hakusan-jo Castle is identified as a typical castle of the Takeda Clan.