Yamata-no-Orochi is the monstrous eight-forked serpent of Izumo province, described in the Kojiki and Nihon Shoki as a creature vast enough to sprawl across eight valleys and eight hills:
頭尾各有八岐。眼如赤酸醤。〈赤酸醤。此云阿箇箇鵝知。〉松栢生於背上。而蔓延於八丘八谷之間
“It had an eight-forked head and an eight-forked tail; its eyes were red, like the winter-cherry; and on its back firs and cypresses were growing. As it crawled it extended over a space of eight hills and eight valleys.” — Nihon Shoki, Book I; English tr. W. G. Aston, Nihongi (1896)
Every year it descends from the mountains along the Hi River and devours one daughter of the earthly deities Ashinazuchi and Tenazuchi; by the time the exiled storm god Susanoo arrives, only their last daughter, Kushinada-hime, remains. Susanoo hides her by transforming her into a comb worn in his hair, then has eight vats of specially refined sake set out. The serpent plunges its eight heads into the liquor and falls into a drunken stupor, whereupon Susanoo hacks it to pieces. Cutting into its middle tail, his own blade notches against something harder within: a great sword later named Kusanagi-no-Tsurugi, which Susanoo presents to Amaterasu as a gift of reconciliation and which becomes one of the Three Sacred Treasures of the Imperial Regalia. The Hi River is said to run red with the serpent’s blood, and Susanoo marries Kushinada-hime and settles in Izumo, composing what tradition holds to be the first poem in the Japanese language.
