Prince Yamatotakeru, originally Prince Ousu, was a Japanese legendary prince of the Yamato dynasty, son of Keikô of Yamato, a legendary monarch who is traditionally counted as the 12th Tennō or Emperor of Japan. The tragic tale of this impressive figure is told in the Japanese chronicles Kojiki and Nihon Shoki. One of his sons later became Chûai, traditionally counted as the 14th Emperor of Japan.
Prince Ousu slew his elder brother Ōusu. His father, the emperor Keikō, feared his brutal temperament. The father plotted to have his son die in battle and sent him to Izumo Province, today the eastern part of Shimane Prefecture, and then the land of Kumaso, today Kumamoto Prefecture. But Ousu succeeded in defeating his enemies, in the latter case by cross-dressing as a maid servant attendant at a drinking party. One of the enemies he defeated praised him and gave him the title Yamatotakeru, meaning The Brave of Yamato.