The Crown Prince's First Love Was Fake

Lirith, a maid, agrees to marry the neighboring country's Crown Prince—known as a murderous demon—in place of the princess who looks exactly like her, all to repay a debt of gratitude. Though she was prepared to die by the Prince's hands for the sake of the princess, the Crown Prince ends up falling in love with her instead. But she's just a maid pretending to be Princess Lirith...