Child of the Izumo clan, Susa was one of the few spared when the Yamato clan slaughtered the village fearing the Izumo might up rise against them. Son of Genkaku and brother to Himiko, Susa's father set out to make his son the ruler of the shattered Izumo people and to avenge those who had fallen... and to be reborn as the god Susa-no-o. The god heard Genkaku's plea, and Yamato no Orochi awoke to bestow his power on Susa, and in a cruel twist his sister Himiko. For the power of the god to truly awaken in Susa, he would need to kill his sister.

Susa's mother, sensing the desperation of her husband, helped Himiko to escape as she confronted Genkaku. Prepared to kill him, knowing he would sacrifice their daughter for his crusade against Yamato, Genkaku instead killed his wife as he set out to relocate his daughter for the sacrifice.

Eighteen years go by before Susa and his sister are reunited, with her now the final step before Susa can claim his true power. Genkaku is eager to complete the process, and against his son's will eventually forces him kill Himiko. The pair then head up a direct assault on the Yamato capital, breaking in and stealing the Ame no Murakumo sword. With the weapon at hand, lighting strikes the boy as he begins to take on the appearance of a god.

Birthed in a flash of lighting from Yamato no Orochi, the instrument of Genkaku's revenge was finally realized. Susa transformed into a hulking beast whose body shows signs of both Yamato no Orochi's power, with a reptilian right arm and a scaly neck, and the fallen hero Susa-no-o. The creature posses tremendous power while in possession of the Ame no Murakumo sword, able to destroy the capital of Yamato in a single sword stroke, sending out shockwaves that detonated nearby structures and sent fissures through the streets, causing the capital's citizens to plummet to their doom.

Sensing that Susa-no-o has finally been released, Seimei and Hiromasa set out to wake the god Amaterasu, in hopes that she will revert Susa back to his human form. The two descend on the resting place of Amaterasu in Ama no Iwato, and begin performing the ritual to call forth the god. However, Susa senses Amaterasu beginning to stir out of her slumber, and goes to Ama no Iwato to confront Seimei and Hiromasa. Upon arriving, though, Susa is paralyzed by Hiromasa playing his flute, as the hulking creature is reminded of his life as a human and lays down his sword. However, his father, Genkaku, is waiting behind him. Taking his son's sword, Genkaku does battle with Seimei, until he runs the Yin-Yang master through with the Ame no Murakumo sword. Fortunately, the blood of Seimei completes the ritual, and Amaterasu is awoken. As hoped, Susa-no-o converts back into a human and goes with Amaterasu back to heaven.