The sword's mythology is told in the Kojiki and Nihon Shoki, the two eighth-century chronicles that underpin Shinto. The storm god Susanoo, banished from heaven, slays the eight-forked serpent Yamata-no-Orochi and finds a blade in its tail, which he offers to his sister the sun goddess Amaterasu. Generations later the sword is entrusted to the warrior-prince Yamato Takeru; ambushed in a burning field, he cuts down the grass around him and turns the fire back on his enemies, and the blade takes the name Kusanagi, grass-cutter.
When Yamato Takeru dies, his consort Miyasuhime enshrines the sword at Atsuta, which tradition dates to the reign of Emperor Keiko. Whatever the legendary chronology, the point is theological: together with the mirror kept at Ise and the jewel at the imperial palace, the sword is one of the Three Sacred Treasures, the regalia whose possession marks the legitimate sovereign. Atsuta is thus not merely a famous shrine but the keeper of a symbol of the state itself.