Nao, who had been living a quiet otaku life in the countryside, decided to move to Tokyo after graduating from college. With no job or place to live lined up, she temporarily stays at her sister's home. However, her sister and brother-in-law's sex life is far more intense than she imagined. Nao becomes captivated by the sight of her sister's body rocking violently with each powerful thrust, letting out scream-like cries with every orgasm. Unable to control herself, Nao gets caught up in the shocking scene, her pussy naturally growing wet. Overwhelmed by uncontrollable desire, she finally takes a bold step forward...