A genuine masochist breaks into sobs under merciless, thorough training. Before she realized it, she had lost interest in ordinary sex and began to find mere intercourse boring. What could have triggered this change? Deep down, she believes it's punishment for sins she's accumulated over time. One day, a casual partner jokingly slapped her back and buttocks—and to her own disbelief, she became intensely aroused. From today onward, she begs for relentless punishment. As a submissive woman, she wants her unbearable desires finally set free.