I Abandoned My Engagement Because My Sister Is a Tragic Heroine, but Somehow I Became Entangled with a Righteous Prince (Manga) Vol. 2

"Leia's sister, Jill, makes Leia out to be a villain. Suspicious of the rumors, Prince Eric proposes that Leia live with him in the palace as his guard. Witnessing the saintly Leia's honesty and sincerity, he apologizes for his rudeness and begins to take an interest in her. Jill, however, is not happy about this, nor is she happy about her own worsening circumstances when the enigmatic Duke Berglein appears!" --