In a distant past, the world was destroyed by the Overfiend, the supreme deity of all realms. He vowed to return after 100 years and restore his realm. However, something has gone awry, and now he is born prematurely, awaiting the arrival of his natural enemy, the Lord of Chaos. His only hope for survival are Amano Jyaku and Megumi. But destiny has taken an unexpected turn as a new breed of half-demon beast creatures have emerged.
As Amano investigates the appearance of the Lord of Chaos in Azuma's kingdom, he is drawn into Caesar's grand plans to conquer the world. Meanwhile, a demon beast slave rebellion and the return of Munhihausen pose a significant threat to humanity. It falls upon Amano and Buju, the demon beast, to save the world from another catastrophic destruction. The fate of Earth and its inhabitants hangs in the balance as they await the arrival of the Lord of Chaos.