A maid named Elie is forced to serve as a substitute for her mistress, the princess, and is married off to the Demon King. If anyone discovers she is a fake princess, the魔族 will execute her. Elie decides to behave in an unlikable manner to keep the demons at a distance, hoping to endure for just three years. However, the more she tries to be disliked, the more the Demon King inexplicably begins to dote on her. A love that starts from being a stand-in questions whether it is real or fake.

The story follows Elie as she navigates her new life in the Demon King's castle. After she is welcomed as the bride, she must face new trials, specifically challenges from the Four Great Demon Lords. No one who has undertaken these trials is said to have returned alive. Her first trial is against Algodakarl, the Star-Shattering Ogre.

During a demon clan ritual, Elie schemes to lose on purpose in an attempt to make the Demon King dislike her. Ironically, this action only captures the Demon King's heart even more. The more she tries to create distance, the deeper his affection for her grows, causing Elie's own feelings to begin changing as she experiences his kindness.

As Elie continues to wear the mask of a villainess to achieve peace between humans and demons, her relationship with the Demon King, which started as a lie, gradually transforms into a genuine bond. However, she is confronted with the harsh reality of their different races when she witnesses the Demon King's cruel, undeniable instincts. Despite her wavering heart, a human army marches toward the castle as she struggles to continue believing in him.