After arriving on the island, the Mystery Club discover mysterious tablets with things like “Detective” and “Murderer” written on them. They initially see it as a tasteless prank, but later that night, the tablet reading “First Victim” ends up on somebody’s door, and the group is forced into solving a real mystery… Meanwhile, on the mainland, Kawaminami and Shimada are getting closer to the secret of the island after receiving letters from Seiji Nakamura, who’s supposed to be dead…!!