Wakayama Castle (Wakayama-jō) in Wakayama, Wakayama Prefecture, Japan, sits at the mouth of the Kii River. Originally Ōta castle, home of the Saiga Ikki, it was captured by Toyotomi Hideyoshi in 1585, during the Siege of Negoroji; many monks from Negoroji sought refuge in Ōta, which was soon destroyed by flood. Hideyoshi ordered the building of dams on three sides of the castle, focusing the rainwaters and diverting the river to ruin the castle. As hunger set in, the samurai, monks, and peasants inside Ōta surrendered, and fifty warrior monks led a final charge against Hideyoshi's army, committing honorable suicide.
Ōta was rebuilt as a temple for the Shinshu branch of Japanese Buddhism, severed from its history as a home to warrior monks. Wakayama Castle was then built on the same site, under the supervision of Toyotomi Hidenaga, Hideyoshi's brother, with Tōdō Takatora's participation. Asano Yoshinaga arrived in 1600 to serve as feudal lord, under Tokugawa Ieyasu. The castle was later attacked, in 1615, by forces loyal to Toyotomi Hideyori, who were trying to end the siege of Osaka.