Jimi Hime to Kuro Neko no, Emmanna Konyaku Haki

Seren, the eldest daughter of a duke family, has been compared to her sister Marietta, who is said to be an exquisite beauty, and has grown up being called the “plain princess”. She overhears her fiancé, Prince Helios, and his friends talking about how Marietta should be the princess consort instead of Seren.