[1] During the Muromachi period, the Imagawa clan ruled Suruga and Tōtōmi Provinces from their base at Sunpu (modern-day Shizuoka City).

Takeda Katsuyori established himself at the former Imagawa stronghold of Takatenjin Castle and resisted all efforts by the Tokugawa armies to dislodge him.

[2] Following the establishment of the Tokugawa shogunate, the castle was expanded and modernized with water moats connecting to the sea and stone facing on its formerly earthen ramparts.

Yokosuka Castle was noteworthy in that it used rounded boulders from the Tenryū River in the walls of its moats, instead of cut stone.

[2] Today, a portion of the moats and earthen walls remain, and a local history museum has been built within the site of the former main bailey.