Tsuruta, a single Tokyo Metropolitan Government employee, has a hobby of groping. One day, a woman, suddenly leaves him a note and leaves. The note reads, "Professional groper, please contact me immediately." Suspecting that this is a sting operation, Tsuruta does not contact her, and the woman, Eiko, begins to tail him, and Tsuruta is finally caught by her. Eiko asks Tsuruta to cooperate with a study on "sexual crimes and culture" being carried out by Seiichi, the heir to a wealthy family whom he has served for generations. Seiichi, who wants to learn about groping philosophy, follows Tsuruta onto the train. Eventually, he improves his skills as a molester, while Tsuruta is attracted to Eiko. However, Seiichi's actions escalate in a bad direction...