Ken's younger sister, Sayuri Kanzaki, comes to Tokyo. She says she wants to quit her dangerous job as a detective and go home with her. But then something strange happens in the underground mall at Shinjuku Station where the two of them are. There's a power outage and an explosion caused by a gas leak. They try to escape to the surface, but Ken and Sayuri are trapped inside. Ken can't suit up in front of his sister...