What is the plan of the suspect who utterly destroys the girls? The key word is 'Mayumi'. The girls become the unwilling subjects of an experiment. In this hellish experience, they reach the limits of both body and soul. Their individual lustful desires explode from within!

They find out that Hiroki is a donor for an experiment of multiple personalities. His alter ego has been replaced with professor Tadokoro's who was thought to have died in the accident. Hiroki tries to experiment on Runa. Shiori finds out and becomes enraged. Mio tries to stop the experiments but is instead victimized by Hiroki.