Maria, the daughter of a duke, always married with the certainty that she would inherit her father's dukedom. Therefore, she focused entirely on learning martial arts and strengthening herself, always putting off matters like marriage. But the story takes a turn when a younger brother is born, shattering Maria's dream of becoming an heir. Now Maria has decided to marry, but she's a little late in the game. Will there still be any worthy sons left? She goes to a neighboring country to try it, but the Crown Prince announces publicly that he's breaking off his engagement to Maria! Maria is stunned because there was no engagement at all—in fact, the Prince mistook her for another girl. When this mistake is cleared up and the Prince sees Maria single-handedly knock out an entire gang of bandits, his heart melts. It seems the Prince has a liking for such fearless and "ass-kicking" women!