A prince of Emperor Keikō (the 12th reign) recorded in the Kojiki and Nihon Shoki. His given name was Ousu no Mikoto; tradition holds he was one of twin sons. In childhood he killed his twin brother Ousu with his own hands, frightening Emperor Keikō. In the western campaigns he demonstrated cunning by approaching the Kumaso chiefs disguised as a woman and slaying them at a banquet, and later deceived Izumo Takeru with a wooden sword — portrayed throughout as a hero of both valor and stratagem. In the eastern campaigns he pacified the fierce deities of Sagami and Kazusa and conquered the Emishi of each region. The tragic story of his consort Ototachibana-hime, who threw herself into the surging sea at Hashirimizu to calm the sea deity, is especially famous. On the return journey the mountain deity of Mount Ibuki struck him with illness, and he is said to have transformed into a white bird at Nobono. Enshrined at many sites across Japan as the hero who conquered east and west, having received the Kusanagi sword from Ise Jingu.

A heroic figure of contradictions—matchless in battle yet deeply sensitive. He mourned his consort's death in verse while remaining undefeated in war. Deeply lonely and homesick throughout long campaigns, he harboured complex feelings toward his father throughout his legendary life.

Handed down as a symbol of the Yamato court's unification of the realm; shrines dedicated to him exist throughout Japan, including Atsuta Jingu. The Kusanagi sword, one of the Three Imperial Regalia, is enshrined at Atsuta to this day. He represents the archetypal "hero" in Japanese legendary tradition.