Just as the title says, this was a series where the protagonist reincarnates into the body of a villainess. I can't remember if it was a book series she'd been reading or a game, but I feel that it was almost certainly one or the other. At least I'm fairly certain it was an isekai. The villainess is the daughter of nobility (of course) and she was considered to be fat and plain looking, however once the prince broke up with her she decided to change her way she dressed and did her makeup. She noted that she had always tried to downplay her large chest in the past by binding it or some similar type of garment, but all this did was made her chest into one large slope on her stomach, making her look fat. I remember at the time wondering how big her chest would have to be to accomplish this and how uncomfortable that would've been. She has a brother, but that's about all I can remember. I can't remember if I liked it or not, but it's bugging me that I can't remember which series this is. I've been going through my read stuff and can't find it yet, but I have quite a few read series so it's possible I could've missed it. Any help would be appreciated!