A nineteen-year-old girl who wants to die. A nineteen-year-old boy who wants to live. I want to spend it with you. ‘Our beautiful Summer’ that will never come back.

Choi Yeo-Reum (Jang Gyu-Ri) is a 19 year old high school student. When her parents were about to get divorced, they fought over having the other person take custody of her. In the end, her mother took her and they lived together. One day, her mother told her "You're all grown up now. You can live on your own." Her mother then got remarried and left 19 year old Choi Yeo-Reum. She is now all by herself and moves to her new home. On a summer day, she learns that her birth was a burden to her parents. She feels miserable and wants to die. On the day that she decides to take her own life, she meets her neighbors Na A-Reum (Yoo Young-Jae), Na Da-Woon (Son Sang-Yeon) and Na Woo-Ri (Kim Min-Ki). They are triplets.