Majin Koushaku to no Himitsu no Keiyaku: Densetsu no Dai Akujo no Umarekawari desu ga, Majin ni Dekiai Sareteimasu

"I must free you from the constraints of your humanity..." An old legend exists of two twins, the saint and the wicked woman. The qualities of those two twins have been found again in two by the name of Aurelia and Deanna. Aurelia was deemed to be the saint quickly enough by her appearance, while Deanna was made to be the wicked woman and t*rtured by her family. One day, while Deanna is again framed by her sister to be the wicked woman, the famed Duke Lilburne comes to help her. However, the duke shows himself to be something beyond human... a sorcerer?! (Source: MangaPlaza)