On a day that Harin thought was the worst, she reunites with her childhood friend Eunju, with whom she had cut ties. Eunju, who used to be a bit carefree, now seems unfamiliar to Harin as she has shortened her skirt and put on perfume. However, the passage of time is something that cannot be ignored, and Harin gradually finds herself getting caught up in Eunju's pace. She thought she wouldn't have the complicated feelings of adolescence, but the changed Eunju continues to stir Harin's heart, which had been as calm as a lake. Will the two of them be able to score high in their first love?