18-year-old schoolgirl Karen Hazuki holds a responsible position as student council president, but one day she discovers the existence of a hidden BDSM club lurking in the shadows of her school. What begins as a chance encounter draws her deeper into this secret world. Through her experiences as a submissive, she gradually unleashes her long-repressed masochistic desires, spending every after-school hour at the club. Initially unfamiliar with the concept of BDSM, Karen becomes increasingly captivated by its allure, devoting her youth to this newfound passion. Comprising four parts, the series portrays her transformation and personal evolution.