Ane no Hikitateyaku ni Tesshite Kimashita ga, Kyou de Yamemasu

According to her childhood promise, Charlotte has been devoting herself to helping her sister. She has endured no matter how foolish it seems, but when she enters school, she breaks. Her sister makes a fool of Charlotte at the school. It is so bad that even the most excellent sister can't take it, and Charlotte becomes isolated as soon as she enters school. If the next three years are wasted as it is, the viscount daughter Charlotte has no future. Because if she can't find a fiancé by the time she graduates from school, Charlotte, the daughter of a weak aristocrat, has no happy future. If she goes on like this, she will marry an old man who is as old as her father. Weighing her relationship with her sister and her future, Charlotte makes a decision. "I want to marry a nice person and live a peaceful life! So I'll quit being my sister's foil today!" Charlotte, who quit being her sister's foil, shows her true ability and overwhelms even the teachers! Charlotte, who knows neither restraint nor hesitation, pushes forward to grasp a happy future! (Source: Shousetsuka ni Narou, translated)