When Hana, his stepsister, comes to stay over, Yuichi is filled with excitement. Seeing her again after so long, he can't take his eyes off her—she's still as busty as ever, her alluring figure captivating his gaze. That night, Hana accidentally witnesses her younger sister and brother-in-law having sex. Already distant from her own husband, the incident leaves her emotionally unsettled, unable to sleep. The next day, returning drunk from a class reunion, Hana is deeply shaken by what she saw the previous night and turns to Yuichi for comfort. In a seductive voice, she whispers, "I've reached my limit..." Overcome by desire, Yuichi finds himself powerless against his voluptuous and irresistible stepsister.