Cinderella no Giri Ane ni Tensei shitakedo Futari no Ouji ni Dekiaisareteimasu

Atra has been reincarnated as Cinderella's stepsister. She is fed up with the life of a "bullying stepsister" as in the story, and wants to be free as soon as the prince and Cinderella are married without getting in their way! She spent her days wishing that the prince and Cinderella would get married soon and she would be free.
When the night of the ball finally arrives, an unexpected turn of events follows, and her life takes a 180-degree turn to "being loved"!