After a summer ruled by sex, Niiyama returns to ordinary life but cannot forget those wild days. A handsome newcomer, Sota, turns out to be the childhood friend who once shared naughty games with her and still regards her as his first love. Though she thinks of him like a younger brother and feels guilty about fantasizing, desire keeps intruding. Then Mikami, the boy she liked in middle school, reappears at her prep school and draws her to karaoke with constant dirty talk. Her buried hunger erupts, pulling her back into sex until she feels consumed and can no longer stop herself. At that lowest point, the sincere Sota returns, forcing Niiyama to choose what future awaits her as she steps toward adulthood.