​Private detective Reiji is approached by a mysterious girl with a plea to find the true her. Coinciding with this request, a series of gruesome murders unfold, with two female students from the girls’ high school, where Reiji’s younger sister attends, going missing. The vice principal of the school, Tokio, asks Reiji to investigate the disappearances. Juggling multiple cases, Reiji takes on a secret identity and begins working undercover at the school. It is there that he reunites with Toko, who had previously asked him to find her true self. As the killings continue, a tragic cycle emerges. Can a girl’s smile be the key to unraveling this spiral of tragedy?​