Hiiragi Retsu is a private detective. He works in his tiny agency with his fiancee Mizuki as an assistant. One day his office building neighbour, a doctor named Kei, introduces him to a client - a woman who was just raped named Reiko. She wants Retsu to find the perpetrator because the police are ineffective. It turns out, not only other women were attacked, but all of them are from the same high school class as Retsu, Mizuki, Reiko, and Kei. Find the culprit in this detective investigation.