Promises are meant to be broken. This is a story about Song Mirae, a third year high school student who's trying to move on from her first love. Along the way, she finds herself falling in love with a man with few words, Choi Seunghyun, although their relationship wasn't that good from the start. They said that time heals wounds, and it really did. Day by day, their love grew stronger, they made promises with each other, they promised to stay loyal, but when they come across challenges, will they stay true to the promises? Are they able to withstand the hardships and have a happy ending?