Kana lives with her younger sister Nagisa and Nagisa’s adult husband Keita, who moved into the sisters’ home after the wedding. Far from resenting him, Kana is secretly delighted to have a cute younger brother-in-law. One night, she dozes off on the last train home from work and senses someone staring. Opening her eyes, she finds Keita fixated on her lower body and stroking his cock. Shock quickly turns to arousal, and Kana lifts her own skirt to flash her panties and deliberately tempt him.