Junichi is an average university student. He doesn't have a girlfriend, but enjoys his school life with his close friend, Yui. One day, he finds a girl groping a man's body when he is on the train. Train molester...? The girl keeps groping and the man finally ejaculates.... Is that a dream...? On the next day, when he gets on the crowded train, he finds the girl. The girl suddenly starts groping his body and he soon ejaculates.... Her name is Ai and recruits him into her circle called the "Chikan (molestation) Circle", which includes members who want to molest or be molested. Junichi is interested in Ai herself, so he decides to join it. However, he needs to pass the test to join the circle. The test is to recruit a girl, in other words, to molest a girl who wants to be molested and make her understand the pleasure of being molested.... Junichi's target girl is Yui.... He hesitates at first, but he, who is addicted to Chikan, makes up his mind to take the test. Like this, his Chikan life starts....