Kagesuke Shōni serves as the younger brother of the Shōni clan shugo governing Tsushima Island during the 1274 Mongol invasion. He briefly appears disguised as a Buddhist monk on Tsushima, where he encounters the exiled samurai Kuchii Jinzaburō and vows to dispatch mainland reinforcements against the Mongol assault. Later, Kagesuke works to fulfill this pledge by rallying forces at Dazaifu, Japan's southwestern military-administrative center, reflecting the Shōni clan's historical command in defending against the Mongol invasions.