Saori, an innocent 18-year-old, finds herself in a tense situation with her stepbrother. Their shared space ignites an uncomfortable awareness of each other's bodies. One evening, Saori's curiosity gets the better of her, and she sneaks a peek at her stepbrother masturbating. His size surprises her, and she can't help but imagine how it would feel inside her virgin pussy. Their encounters become more frequent, each time pushing the boundaries of their taboo desire.