The Kojiki, compiled in 712 CE, and the Nihon Shoki, compiled in 720 CE, both place the encounter in Izumo province, on the west coast of Japan, after Susanoo has been cast out of the High Plain of Heaven for his violent conduct toward his sister Amaterasu. Descending to earth beside the Hi River, he meets an old couple weeping over their last surviving daughter, Kushinada hime, and learns that a monstrous serpent has devoured her seven sisters one year at a time and is due to return for her.
Susanoo offers to fight it if he may marry the girl, then hides her by transforming her into a comb he wears in his hair, a detail scholars have read as evidence of very old ritual logic linking combs, hair and protective magic. His plan is not brute combat but intoxication: eight vats of sake, brewed eightfold strong, set behind an eightfold fence with eight gateways, one vat to a gate. The eight-headed serpent obligingly puts a head in each vat, drinks itself insensible, and Susanoo dispatches it with his sword while it sleeps. The number eight recurs so insistently across the tale, in heads, tails, hills, valleys, fences, gates and vats, that many readers take it as a formal marker of overwhelming scale rather than a literal count, the mythic equivalent of saying the serpent was simply enormous.