In her ordinary yet happy daily life, Reiko feels a quiet loneliness, as if losing the sparkle of being a woman. To escape the boredom, she starts using social media and meets a man. His occasional sadistic messages captivate her, making her heart race. When she finally meets him, she opens the door to forbidden desires and submits to tight bondage training. A single mistake binds her body with rough ropes, shattering the rationality of the married woman, as she falls deeper under his sadistic control. Yielding to these impulses, she begins walking a path from which there is no return.