A Fairy-Tale Ending for a Fake

From an orphan, I suddenly became the empire's sole princess overnight. I read books until my eyes bled, mastered etiquette, and cultivated refinement. I endured the nobles' sneers, the Three Brothers' tyranny, and the servants' disdain. Ten years later. They say they found the real princess presumed dead. I resigned myself and tried to leave as calmly as possible. “Sister! Don't worry! From now on, I'll protect you!” The real princess likes me too much! “…Thank you.” The duke, whom I thought wasn't on my side, treats me like his own daughter, “Is there another reason? I just wanted to dance with the princess.” Even the prince, plagued by bad rumors, resorts to schemes. Isn't this something only seen in stories?