Yeon-hee, who hasn't changed her hair and isn't ready for the first night, gives sex advice to her friend over the phone and calls her boyfriend over to have sex. Unlike the first time, he is overflowing with libido and visits her office to have sex. Ji-ho is worried about her girlfriend. Although they are friends, Chae-ah and Seon-woo end up having sex after drinking during the day. Different sex stories of 4 couples.