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 died four years ago. And four years later, he goes to Hee-wan as a grim reaper and tells her that she will die in a week. Hee-wan can’t believe what she sees and hears and refuses to talk to Ram-woo. As Hee-wan is lethargic and wants to do nothing before she dies, Ram-woo suggests that Hee-wan complete his bucket list together.

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.

Hee-wan cries and tells Ram-woo that she couldn’t forgive herself and that the past memories alone give her enough pain. She wants to quit completing the bucket list with Ram-woo. Meanwhile, Hee-wan goes to see Hong-seok. However, Hong-seok doesn’t seem happy to see her.

Hee-wan goes to Ho-gyeong and asks about Jeong-suk’s whereabouts, but she refuses to tell Hee-wan. Hee-wan really wants to see Jeong-suk and tells her the truth that Ram-woo’s death was her fault, and that it was not because of Jeong-suk. However, Ram-woo thinks Hee-wan should move on and stop feeling guilty.

Although she wastes most of her week, Hee-wan still has one more day to say goodbye to the world. She prepares gifts for Hee-ju and her father. With Ram-woo, Hee-wan wants to go on a typical, predictable date with him. Meanwhile, Hee-wan keeps getting calls from Yeong-hyeon.