Otowa and her husband return to the husband's parents' home in Tokyo. Yusuke, the brother-in-law who is busy caring for Shigeo, leading a life without women, is captivated by Reiko's sex appeal. Yusuke sniffs Reiko's underwear, which he has left in the clothes basket. The female scent emanating from the mature woman's body destroys Yusuke's reason and awakens his reproductive instinct. The lascivious smell of the brother-in-law and sister-in-law as they make love passionately, covered in each other's sweat and bodily fluids, permeates deep into the tatami mat...