Sara, a lady-in-waiting to the princess of the Saleille Kingdom, is ordered by the king to marry the crown prince of an enemy country in her mistress's stead. She believes it's all for the sake of the princess she serves, but the princess steals Sara's lover, and the lover insults Sara, calling her 'unlovable'. Betrayed by those she trusted, Sara doesn't fall into despair. Instead, she declares, "I will absolutely, definitely be happy in Ferie!" She says goodbye to the princess she respected and the lover she adored. As Princess Ermine, Sara will find happiness with the neighboring country's crown prince (who is reclusive, misanthropic, and always wears a mask)! *Main story complete. For "The Princess's Smile: Extra Story," please see the series list.