in my opinion its wrong in many ways. when you lose so much weight in a short time, I think you skin would be a bit... flabby? and if she lose weight with sword fighting- where are her muscles? she wouldnt be so skinny (a sword has more weight then an epee or rapier). just beeing skinny doesnt mean you're automatically a beauty. dunno humans are diffrent. we should never confuse a bit overweight with a serious illness of (or with) high obesity
Let's just say: If the story starts with reincarnation/transmigration and involves magic in general, we better not expect realism at any point. X'D
But yeah, loosing that much weight in just 3 months and not having tons of flabby skin hang off of you if never gonna happen irl. I hope no little girls read this and think this is how it'll go...
looks like the art from sura's lover, or not?