Every year, the Ushiromiya family gathers on Rokkenjima at the request of their eccentric patriarch, Kinzou, whose health is failing. Most relatives believe his time is running out. As a fierce typhoon batters the island, tensions over inheritance and succession escalate within the family. Battler, Kinzou’s grandson, returns after six years away, expecting a peaceful reunion. Instead, Kinzou devises a peculiar game, challenging the family to find his hidden treasure, with the winner gaining control of the family. The game takes a dark turn when participants are threatened as sacrifices to revive the legendary Millennial Witch, Beatrice. Despite being a staunch skeptic, Battler must confront the possibility of supernatural forces or a murderer among them as the body count rises.