"Even If My Older Sister Hates Me, I Love Her Dearly! ~The Heroine Dotes on the Villainous Young Lady~"

My beloved older sister, who was more beautiful and kind than anyone else, changed after becoming engaged to the Third Prince. She transformed into a cruel and ruthless stepsister, and began to mistreat me, trying to drive me out of the Marquis household. My textbooks were torn to shreds, I was doused with water in the middle of winter, and pushed down the stairs—such days of harsh mistreatment continued. However, my sister had a shocking reason hidden away that made her act this way——. (※Thank you to those who reported typos.)