The occurred in 1578, when the army of Mōri Terumoto attacked and captured the castle of Kōzuki in Harima Province. Kōzuki had been taken by Toyotomi Hideyoshi the previous year and entrusted to Amago Katsuhisa. When it fell to the Mōri, Amago committed hara-kiri. Amago's loyal and heroic general Yamanaka Yukimori was captured and killed in the battle. It is popularly believed in Japan that Yamanaka Shikanosuke, Amago's general, "sold" Amago's life, for the safety of his own men.