My sister-in-law moved in today...

Yasuyuki, his older brother who was forced out of his company, and his wife Riko, who came to live with her parents. Riko's younger brother, Shinsuke, is captivated by Riko's cute appearance as she works hard at the household chores as soon as she arrives. Then, without thinking, he steals Riko's underwear while she is taking a bath. Then, that night, Shinsuke asks Riko about her underwear as she sleeps close to him without a futon. When he apologized honestly and returned the underwear to Shinsuke, Rico started touching Shinsuke's crotch... It was like a dream. However, the happiness is short-lived as Riko gets into trouble with the moving company.