On a remote island in the middle of the ocean, two rival clans maintain an uneasy peace through a barbaric annual tradition. The powerful Miyaru Clan, said to be descendants of sharks, demands a yearly sacrifice from the weaker Tangata Clan: one young adult must be offered as a bride to keep the peace. Avel, the son of the Tangata patriarch, has grown increasingly dissatisfied with this humiliating arrangement and intends to defy the ancient law.

Before Avel can put his plan into action, he is attacked by a jungle beast. He is rescued by Tukiri, a member of the Miyaru Clan who appears friendly and gentle, completely unlike the monstrous reputation of his people. Avel begins to lower his guard, but when Tukiri notices Avel's bleeding wound, his personality flips. He loses his humanity, becoming beastly in an entirely different way as his predatory shark instincts take over.

For the Tangata Clan, this encounter carries a unique and terrifying consequence. Due to their special physiology, a Tangata individual's first intimate experience determines their permanent gender. If Avel is taken as a woman, he will biologically become a woman. As the next in line to become clan patriarch, Avel fears the repercussions for his future and his people, even as he finds himself drowning in waves of unfamiliar pleasure.

The story follows Avel and Tukiri as their fates become intertwined through this accidental and steamy encounter that threatens to upend the longstanding order between the two clans. The manga explores themes of identity, duty, and desire against a backdrop of ancestral rituals and clan warfare. The narrative continues beyond the initial encounter, with a sequel series that was published from May 2022 to July 2023, expanding on the consequences of their bond and the fragile peace between the shark clan and their human sacrifices.