This monster is based on Susanoo (also romanized as Susa-no-Ō-no-Mikoto, Susano-o, Susa-no-Ō, and Susanowo), who in Shinto is the god of the sea and storms. Susano'o is the brother of Amaterasu, the goddess of the sun, and of Tsukuyomi, the god of the moon. All three were spawned from Izanagi, when he washed his face clean of the pollutants of Yomi, the underworld. Amaterasu was born when Izanagi washed out his left eye, Tsukuyomi was born from the washing of the right eye, and Susano'o from the washing of the nose.
Susanowo is curiously also known as "Suzanowa", although that may be an incorrect transcription of the name. He is infamous for his connotations as the god of evil and serpents and having been thought to cause storms, having dominion over the sea.
Sources tell of long-standing rivalry between Susano'o and his sister. When he was to leave heaven by orders of Izanagi, he went to bid his sister goodbye. Amaterasu, suspicious, proposed a challenge on the spot: each of them was to transform an object of the other's into people. Amaterasu created three women from Susano'o's sword while he created five men from her necklace. Claiming the men were hers because they were born of her necklace, Susano'o destroyed her rice fields, hurled a flayed pony at her loom, and killed one of her attendants in a fit of rage. Amaterasu, in fury and grief, hid inside Ame-no-Iwata, the "heavenly rock cave", thus effectively hiding the sun for a long period of time.
Though she was persuaded to leave the cave, Susano'o was punished by being banished from heaven. He descended to the province of Izumo, where he met an elderly couple. Seven of their eight daughters had been devoured by the eight-headed serpent Yamata-no-Orochi and it was about to come for the eighth, Kushi-inada-hime. After the couple promised their daughter's hand in marriage to Susano'o, he agreed to slay Orochi. With the aid of eight bowls of sake (one for each head), Susano'o decapitated the monster once it had fallen asleep.
From one of Orochi's tails, Susano'o pulled out a sword, which he named Ame-no-Murakumo-no-Tsurugi ("Heaven's Cloud-Gathering Sword"), later known as the Kusanagi-no-Tsurugi. The sword was presented to Amaterasu as a reconciliation gift and was later given to her descendant Ninigi along with the Yata-no-Kagami (a mirror) and magatama (sacred jewels) as proof of his divine right to rule.