Sandwiched between a talented eldest sister and a beautiful youngest sister, Sakura Odle has always lived as the overlooked second daughter of a noble family. Her quiet life, spent taming small magical beasts, is upended when Prince Kai, the second prince of the kingdom of Killingsheek known as the God of War or Dark God of War, summons her. He declares that the sacred sword has chosen her as its keeper, and she must become his queen.

The reason for her sudden elevation is not love but necessity. Sakura possesses a rare ability to serve as a living sheath for the Sword of Destruction or Demon-Slaying Sword, a powerful weapon that protects the kingdom. She is taken to the prince's estate, not as a true bride but as a functional vessel to hold the blade. Feeling like a bird in a gilded cage, she is expected to simply exist at Kai's side. Despite her cold and distant new husband, Sakura begins to subtly affect him through her innate intelligence, perceptiveness, and gentle kindness. Her compassion slowly thaws Kai’s icy demeanor, causing him to change in unexpected ways as their relationship, born purely from duty, grows into something more. Their love deepens as they clumsily navigate their mutual misunderstanding and the emotional barriers between them, forming a beautiful Cinderella romance where feelings of frustration and affection intertwine.