Koishita Hito wa, Imouto no Kawari ni Shindekure to Itta. ~Imouto Kekkon shita Katakoi Aite ga Naze Imasara Watashi no Moto ni? to Omottara~ (Associated Names)

The noble lady Wisteria was in love with Bright, the beautiful and kind son of a duke. She was determined to become engaged to him and made every effort to do so, despite her bad reputation. However, it was her adoptive younger sister who Bright opened his heart to. One day, her sister was chosen…