Yamanashi, Japan

Koshu (甲州) is a region of Japan, adjacent to Kamakura and Tokyo. It corresponds to the real-world Yamanashi Prefecture, and in some early sources is known simply as Yamanashi Prefecture.

Koshu was overrun by the Huge and largely abandoned during the conflict known as the Koshu Evacuation; some of the former population now lives in evacuation zones. The Garden of Kaiseizan continues to operate within the occupied territory.