The Kojiki traces misogi to a single founding episode. Izanagi, one of the two primal creator deities, has just returned from a failed attempt to retrieve his dead wife Izanami from Yomi, the land of the dead, an underworld visit that has left him defiled by contact with death and decay. Horrified and polluted, he goes to a river mouth in Kyushu and washes himself, and as he removes each piece of clothing and rinses each part of his body, a new kami is born from the act, some from his abandoned garments and ornaments, others directly from the washing itself.
The most consequential of these births come last: washing his left eye produces Amaterasu, the sun goddess and ancestral deity of the imperial line; washing his right eye produces the moon god Tsukuyomi; and washing his nose produces the storm god Susanoo. Misogi is therefore not, in its mythic charter, a minor housekeeping ritual but the very act from which some of Shinto's central deities emerge, and the myth establishes a durable theological logic still cited today: pollution, kegare, is not primarily a matter of moral guilt but of contact with death, illness or other disruptive forces, and cold water washing is the prescribed remedy that restores a person, and by extension a community, to a state fit to approach the kami.