Sara Tsukihi is a married woman who, overwhelmed by work and feeling neglected by her husband, turns to social media to express her loneliness. There, she meets a man who calls himself "Sensei," and begins an affair with him, finding emotional relief in their relationship. However, when her husband suddenly shows her unwavering affection, Sara decides to end the affair. But "Sensei" insists that anal sex doesn't count as cheating, and forcibly draws Sara into an anal hell. This shocking story unfolds in intense detail.