Jimin had always been a runner and he loved to observe people. His favorite time of the day is in the morning when he jogs past a brown piano in the streets where a strange boy always plays. On this one day he wasn't playing...

Kim Jonghyun was only Jonghyun. Kim Kibum became Key to not be only Kibum. One day these both run into each other by coincidence, knowing that they will both never see the other again. But why does Key knock onto the door of only Jonghyun a few days after their first and supposedly last meeting?