Jung Hee-wan is a feisty high school girl. Kim Ram-woo is a transfer student to Eunsung High School. On April Fools' Day, their classmates decide to swap names for a day, and Ram-woo and Hee-wan swap their names. After swapping their names, Hee-wan has her best day. She feels like swapping names with Ram-woo brings her luck, so she wants to keep swapping their names.

Ram-woo and Hee-wan share many memories. Hoping to make her feel better and encourage her to stop isolating herself from the outside world, Ram-woo drags Hee-wan to her college. However, Hee-wan feels unbothered and wants to push Ram-woo away.