So-hee gets ready to visit her mother in Gwangju on her day off, and Book-goo accompanies her for the first time. However, strangely, he seems all too familiar with her place. Seon-jung and Sun-guk are arguing about Sun-guk's birthday dinner with their parents, and Ji-yeon pokes her nose into it to solve the problem. Meanwhile, Ji-goo is worried about Ji-yeon as she cannot get in touch with her.