University student Mari Toujou goes to sleep one night and awakens on a battlefield, blood pouring from her neck. With little time to take stock of the situation, she leads her side to a decisive victory, aiding in the capture of the enemy commander Leon Midal. Only then can she process the bizarre turn of events: she seems to have entered the body of Mary Flau Calkula, a tyrannical queen abhorred by the populace. Due to her arrogant and wasteful ways, her childhood crush Leon led a rebellion against her. However, Leon is now their captive, and Mari can feel the emotions her body once held for him. She wants to prove that she has turned over a new leaf, but remnants of the previous Mary still remain. Working alongside Leon and various men in the castle, Mari aims to foster trust in the monarchy and rebuild her country, and perhaps also realize true love in the process. [Written by MAL Rewrite]