Kazoku ni Yakudatazu to Iwaretsuzuketa Watashi ga, Mashou no Koushaku Kishi-sama no Saiai ni Naru made

Unlike her younger sister who is beautiful and has magical talent, Elma is ordinary and incompetent. One day, while being oppressed by her family, she meets a man whose face is covered with a cloth. He was a knight feared as a "devil" who could steal the sanity of his opponents with his beauty. When the man takes an interest in Elma, who has no magical powers, and learns of her misfortune, he forcibly takes her out of the house?! Gradually, she becomes attracted to his kindness and regains her sealed memories. Apparently, her family has a secret...?!