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.

Minjung, the older sister who was the first love of Cheolsu. Chulsoo is drinking with Minjung who was about to get mixed. The two people who drank do the affair in Min-jung's house. After returning home, Chul-soo meets Young-hun, who was close with Min-jung. Young-hoon is dating his favorite Yuri. After seeing Chul-soo for a long time, I am excited to introduce Yuri. However, Yuri, who was not interested in Yeonghoon, feels crushed by her withdrawal. Young-hoon and Chul-soo are second. Young-hun is surprised when he talks about what happened with Min-jung while drinking. Young-hoon goes to Min-jung right away. Yeonghoon also liked Minjung in the past and has been rejected many times. After drinking, he comes to pick up Min-jung. Min-jung feels sorry for the drunk Young-hun, and teaches Young-hun the real love.

Their neighbors, Young-hoon and Chul-soo, have their first love, Minjung. The innocent glass appears to the two men, and each other's love is mixed. As time goes by, Young-hun finds out that her real love is glass and discusses how to reconcile again. Meanwhile, Chulsoo completes his life in the city and descends to his hometown. Then, by chance, Yeonghoon and Yuri appear in the place of reconciliation, and after seeing such withdrawal, Yeonghoon is very embarrassed and asks why he came back. Cheolsu presents something to Younghoon and Cheolsoo and Yeonghoon Yuri go to Minjung's home, the first love of the two men... The story of the two men and women who cannot see one another begins again.