High school gymnast Do Hyeon is ordered to perform community service as punishment for fighting. While doing this by serving as a library assistant, he meets Su Hyeon, 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. Do Hyeon’s mother, aformer actress, can’t even recognize her own son now due to dementia-most of the time she mistakes him for her manager-and Su Hyeon isn’t who she’s pretending to be. Her real name is Se Yeong, and she’s on a mission to understand the reason behind her friend Su Hyeon’s Self-harm by reading all the books she borrows from the library. Will Do Hyeon carry on with his gymnastics? Can Se Yeong overcome her obsession with her dearly departed friend? Each of them faces new choices.