Orochi, the Eight-Headed Dragon

Emperor Keiko of Yamato harbors a deep loathing for his newborn twin son Ousu and secretly intends to kill him. He enlists the mysterious shaman Tsukinowa to carry out the deed, but Amano Shiratori, the phoenix and the White Bird of the Heavens, foils the attempt. Keiko's sister decides to raise Ousu, shielding him from his father's wrath.

Ten years pass and Genbu and Seiryu, Ousu's aunt's servants, prevent him from entering the mysterious cave. He discovers a comma-shaped gemstone that teleports him to a mysterious realm. There he meets King Bullhead, who prophesies that Ousu will become a god-warrior once he possesses three lights.

As Ousu matures, Keiko pardons him to return to the castle. His mother Inahi dies from a mysterious illness, igniting his brother's rage and leading to a deadly clash. Ousu defends himself and accidentally kills his brother with the gemstone.

Keiko orders Ousu to leave the castle until the barbarians of the Kumaso domain are defeated. He journeys toward their lands and stops at a shrine where he befriends a young priestess named Oto Tachibana, who joins him on the quest.

Ousu, Oto, and their allies raid Kumaso's forces and kill King Kumaso Takeru, who attempts to sacrifice Oto to the god Kumasogami. Ousu defeats him with his gemstone and receives the shrine mirror from Amano.

With Takeru dead, Ousu earns the name Yamato Takeru, but Keiko refuses to fully accept him. His aunt warns of a looming threat: Tsukuyomi's return to endanger the Earth. Ousu prepares for the coming danger.

Tsukinowa's treachery unfolds as he tricks Ousu into surrendering the Sword of Dark Clouds, sealing Tsukuyomi's power. Tsukinowa is revealed to be a fang of Tsukuyomi; he murders Inahi and Ousu's brother, and Ousu mortally wounds Tsukinowa in retaliation.

A solar eclipse darkens the Earth as Tsukuyomi reclaims the Sword of Dark Clouds from Tsukinowa and unleashes chaos. Tsukuyomi's awakening endangers all life, and the balance between light and shadow hangs in the balance.

King Bullhead reveals himself as Susanoo and tells Ousu that his destiny is to destroy Tsukuyomi with Oto's aid. Susanoo tests Ousu by having him pull the Sword of Karasai from a stone, the only weapon capable of killing Tsukuyomi.

Ousu and Oto travel to the Moon to confront Tsukuyomi, who has transformed into Orochi. Amano joins their aerial assault, but they are overwhelmed. Oto sacrifices her life energy to empower Ousu, enabling him to become Utsuno Ikusagami and face Orochi.

Ousu defeats Orochi, who reverts to Tsukuyomi. Oto is revived, and Susanoo instructs him telepathically to seal Tsukuyomi's spirit inside Ousu's gemstone and cast it into outer space, ending the eclipse and restoring sunlight.

With the threat contained, Ousu and Oto prepare to fly home to Earth. Keiko expresses a wish to see Ousu, but they part ways, and Ousu returns the Sword of Dark Clouds to Yamato.