
I hope the little sister burn her household to the ground and make her realize how hard it was for the protagonis

The parents take advantage of her. How are they nice? They make her do the household work (instead of the mother, it's HER job) and she does the social p.r. (the mother and father's job) and she runs the business (the father's job).....so, tell me, considering how fast they sacrificed her to the stranger-lord for their family's status and prosperity, how are they nice?

True, we don't have a lot of background, but we do know that the sister and parents are aware of her nickname and they haven't done anything to defend her publicly---like let people know they are wrong about her, like all the good she does. If my daugher was being called an evil bitch by everyone in town, you think I'm not gonna do my best to counter those rumors and punish people who spread lies, esp if I have power like that family has. The sister knows better--and doesn't correct her friends. They may disagree on social customs, but she knows her sister isn't some villain. The parents, too. They've seen her be hardworking and self-sacrificing. Why are they not clearing her name?
Rei is the true mvp