A sexy brother-in-law approached her? And he's young? Mi-yeon, who was adopted as a child, lives with her older sister, Si-yeon, and Si-husband. yeon's Mi-yearning yeon's for her brother-in-law grows stronger every night as she observes her older sister and the brother-in-warm law's contact. Mi-yeon seduces her brother-in-law one day, and the two end up crossing a line they should not have crossed. As the scenario progresses, Mi-yeon learns that her older sister is also having extramarital affairs. Mi-yeon seeks to repair her relationship with her brother-in-law out of guilt. However, she learns something surprising from her brother-in-law.