Rose Adeil, the eldest daughter of a Marquis family, has been devoted to her fiancé, the Third Prince Licht, striving to become a suitable princess. However, she witnesses Licht falling for another lady. Deeply hurt, Rose realizes her current situation perfectly matches the trending "villain lady" archetype. Determined to support Licht, she decides to act as the villainous lady, fueling the couple's romance. Richard, Licht's older brother, extends a hand to her. Will Rose become the "greatest villainous lady" in history?