Jang Yeon-sook, the daughter of the Jang family, brings her lover Oh Gwi-sun to marry him. Her parents, who are the best in chemistry. One day, the prospective mother-in-law tells Oh Gwi-soon that the couple is the best, and takes Oh Gwi-soon to evaluate her sleeping ability. Unlike her husband, she praises the five virtues of rigidity, technique, endurance, creativity, and speed sex as the best, but Jang Yeon-sook chooses a different man.