Izumi (Akatsuki), who was active overseas as an international investigator, returns to Japan at the request of her former lover. He attempts to discover the secrets of the Shirakaba House, but is captured and sent to Slave Island. There, the daycare worker Megumi (Hayakawa), the female doctor Yuki (Morishita), and Sayaka (Shiina), whom he met during the investigation, are kept as slaves.