Eun-gi's eventful life in a boarding house has begun with the three ladies: a sexy owner of a boarding house, her daughter who is even sexier, and his innocent first love. Eun-gi, a freshman, has found his new place in a boarding house operated by mother and daughter when he came to Seoul to study. His only pleasure is to play along in the unspoken push-and-pull relationship with the mother or the daughter. One day, his first love, Soon-yi, who is innocent and docile, suddenly comes to visit him at the boarding house. With the sexy daughter of the boarding house behind the door, and the curvaceous lady owner of the boarding house in the bathroom next to his room, the 20-year-old virgin Eun-gi's sleepless night begins.

"If we do this, what will you do, Ma'am?"