High school gymnast Dohyeon is ordered to perform community service as punishment for fighting. While doing this by serving as a library assistant, he meets Suhyeon, a schoolgirl who borrows a lot of books. Finding her attractive, he talks to her and they gradually grow closer. This love between a teenage boy and girl looks cheerful enough, but they are both suffering in their own way. Dohyeon's mother, a former actress, can't even recognize her own son now due to dementia-most of the time she mistakes him for her manager-and Suhyeon isn't who she's pretending to be. Her real name is Seyeong, and she's on a mission to understand the reason behind her friend Suhyeon's suicide by reading all the books she borrows from the library. Will Dohyeon carry on with his gymnastics? Can Seyeong overcome her obsession with her dearly departed friend? Each of them face new choices. A teenage love story and coming-of-age film in which the bright and wholesome protagonists bring joy throughout.