Show Hamura transfers to boarding school Yusei Gakuen and meets his little twin brother, Kai Mizou. They were separated when they were children, and Kai lost his memory - to Show! Kai is cautious about Show because he knows what Kai doesn't know. One day, Principal Reiya asks them to look for Nagisa, who is missing. They join some friends and search an abandoned building. Suddenly, monsters show up and attack them! Will they be able to find and save Nagisa?