The story begins with Adel, the eldest daughter of the Duke of Fezandic, facing her usual torment from her younger sister, Lillian. Lillian, spoiled by their parents, demands Adel's debutante dress, escalating her demands to the point where Adel, fed up with years of such treatment, strips off the dress and leaves. Her loyal maid, Ellie, expresses her outrage at Adel's mistreatment, but Adel, accustomed to it, decides she can no longer endure living in such conditions and plans to run away and become a commoner.
While contemplating her escape, Adel is approached by a beautiful young noblewoman named Dianne, who offers her a ride in her carriage. Dianne, sensing Adel's distress and noticing her worn clothing, invites Adel to her home. There, Dianne reveals her intention to help Adel attend her debutante ball, providing her with a beautiful, albeit antique, dress. Adel is overwhelmed by Dianne's kindness and generosity.
At the ball, Adel's presence, along with her borrowed dress, causes a stir. Lillian, enraged, confronts Adel, accusing her of stealing the dress. However, Dianne intervenes, claiming she lent the dress to Adel. The King, who is present, recognizes Dianne and reveals that she is involved in a crucial task for the kingdom. He then commands Adel to assist Dianne, much to the shock of Adel's parents, who had claimed Adel was too ill to attend. This royal decree effectively silences Adel's father and exposes the lies surrounding Adel's supposed frailty.
Later, Dianne explains the true nature of her work. Her family, the Calence family, is cursed. Centuries ago, the King unjustly executed a daughter of the Calence family and her family. Since then, the royal line has suffered misfortune, with male heirs dying prematurely. A prophecy foretold that the curse could only be broken if a daughter of the Calence family, wearing one of the dresses made for her, lived with a prince of the same age until he reached adulthood, thereby purifying the curse through another's possession of the dress. Dianne, living in the ancestral Calence home and wearing these dresses, is fulfilling this role for the ailing Second Prince, Dietliff. Adel's task is to be Dianne's companion for the remaining month until the Prince's birthday, ensuring Dianne doesn't abandon her duty. Adel, accepting this unexpected royal assignment, agrees to help, finding a sense of purpose and a new, albeit unusual, friendship with Dianne.
