It had been three years since her debut in the social circle. The daughter of a count, Melfiera, had been the subject of unpleasant rumours due to her hobby, and was unable to even get engaged. She was told by her father's future wife, who did not think well of her, that if she did not find a fiancé within a year, she would be sent to a convent.

Hearing that, she rushed to attend the autumn party. The truth was, she was not really into it, so she found herself alone at the party where she met the others. In the midst of this, she was attacked by a demonic beast that had been infected by a demonic poison and had gone mad. The man who saved her from the desperate situation was a bloodied man who smiled fearlessly. In fact, this man was the Duke of Galbraith himself, who was also known as the "Mad Duke."