I agree with the idea that Yuria is a reincarnator and that this is probably a media (game, manga, anime, etc) setting in her previous life.
However, I do think that Reika is a villainess in that setting. This can be seen from how others react to her; her family is apparently famous enough and influential enough that even internal students are at the very least much warmer to her than to other new students, if not considering her one of them. Perhaps in that media setting, her family never becomes destitute or at the very least she had an upbriging more befitting of her famous name.
Now I also had a thought. From the looks of it, perhaps Yuria wasn't the 'Heroine'? If we look at it, she's an internal student. On the other hand, Yuuki is a new student and from what Yuria said she is a potential Reika bullying victim. Those are some very cliche qualities of a heroine.
