The former knight's daughter becomes the devil's bride

Nadia, you must marry into the royal family in place of Priscilla." Nadia, a daughter of a margrave who has dedicated herself to the knight order as a knight, is to marry Ethan, the third prince known as the "devil," in place of her stepsister Priscilla. However, the rumored crown prince turns out to be a young man with a kind and delicate heart...!? The two had only intended to stick to a pure marriage that was limited to three years, but gradually they begin to connect with each other. A love story of misunderstandings, a heart-fluttering love story between a former knight and a margrave's daughter, and the crown prince, who is often mistaken for someone with a tough face!