An older brother is left alone at home with his younger sister, Sumire, who is a high school girl. Taking advantage of their parents' absence, Sumire Sumire around the house in messy loungewear, stripping off all her clothes. Her erect nipples are clearly visible without a bra, and her shorts reveal her bushy hair. The older brother becomes aroused by this unconscious temptation, devouring Sumire's body as she sleeps, and even becomes jealous that she is going out on a date, to the point of forcing her to perform oral sex on him. What is the answer that the younger sister gives to her brother who cannot be honest with himself?