She and he were a happy couple, but on the day of the proposal, something happened that both of them could not let go of for the rest of their lives. However, the two people in their lives may have tried to bury their memories in the long river of time, and may one day forget them. However, a phone call brought them back to that memory again and again, and they wondered how they would face each other once they met. The smile at the end may be the smile in that scene.