Having grown up in the impoverished slums of Ebelstein, Derek understands better than anyone that talent alone is not enough to overcome the gap between social classes. Through relentless effort, painful experiences, and years of discipline, he manages to become a second-rate mage and survives by working as a mercenary. Though his achievements are hard-earned, society still refuses to fully acknowledge someone of his background.

His life unexpectedly changes when he is hired to tutor Diella Duplain, the youngest daughter of a prestigious noble family. Despite her noble bloodline, Diella is unable to properly use magic, making her a constant disappointment in the eyes of her family. With exile to a convent looming over her as a final punishment, Derek becomes her last chance to prove herself. However, their relationship gets off to a disastrous start, as Diella’s stubborn and difficult personality constantly clashes with Derek’s strict and realistic nature.

As the two spend more time together, they gradually begin challenging each other’s beliefs and insecurities. Together, they may discover that failure is not determined by status, talent, or reputation—and that perhaps there is no such thing as a truly “bad” lady after all.