An Osaka hospital drama unravels as myth and medicine collide. A seasoned surgeon known as Dr. Ukyo Rettsu is confronted by an elderly psychic woman pleading for the removal of a massive cancerous growth. He soon discovers the “cancer” is not a disease but a demon messenger forecasting a long-foretold invasion from 5,000 years ago, and that he may be the prophesied man meant to stop it. The woman's spirit, though she dies, blesses Rettsu with startling new powers—superhuman toughness, speed, and strength—that reshape his life and his sense of responsibility.
To confront the looming threat, Rettsu partners with his lover, Fuyuko Asahina, and together they embark on a quest that spans time and memory. They probe the depths of Japan’s past, chasing clues to an ancient temple where Rettsu must confront and slay a colossal demon. Along the way, their mission broadens into a test of faith and reason, blending science with age-old prophecy as they inch toward a confrontation that could alter humanity’s fate. On their journey, Rettsu faces the Demon of Water and the Demon of Earth as they race to avert a catastrophe that stretches from antiquity to the present.
Their path leads to Kyoto University, where Rettsu seeks counsel from his old ally, Prof. Takase. The professor points them toward the desolate ruins of the Jomon period, suggesting that the ancient demon civilization might still be hidden beneath the earth. In a daring expedition with Asahina, Rettsu uncovers a portal that catapults him back five millennia, placing him in a world ruled by five nun spirits—the Five Goddesses—who pledge their aid in the coming struggle. In this prehistoric era, Rettsu bands with indigenous humans, shielding them from demonic forces and slipping into the demon civilization’s underground realm. He learns the demons’ plan is to leap forward into the future and erase humanity to preserve their own race from extinction.
Back in the present, Rettsu carries out a desperate mission to sever the demon threat once and for all. He destroys the demon horde at the brink of a portal that the unseen demon queen would use to cross into their world, and then completes the work when he returns to today, ending the immediate danger.
Yet the victory is not the end. After a tender reunion with Asahina, Rettsu intends to marry, only to be warned by the Five Goddesses that the demon race is not extinct. The queen still lives, and she has thrived by manipulating history—seducing men across ages to spawn new demons and secretly rebuild her civilization. In a hidden catacomb, Asahina reveals her true identity as the demon queen who adopted a human shell. She proposes to die with Rettsu as an act of tragic love, but the goddesses intervene. Rettsu fights back and defeats her, and Asahina dies proclaiming her love as the curse is finally broken and Rettsu returns to a life where the threat of annihilation has been lifted. The balance between science and myth is restored, and the world breathes a cautious, renewed peace.
