Clearly the implication is that this whole butterfly thing massively fucks with peoples personalities to the point that theyre all slowly turning into psychos with brief flashes of their true self, but thats just too depressing for me so i hope that its just that the culture that the butterflies have established is the fault and reika just became a massive asshole because she got power(this way it would still be reversible).
From what weve learned in chapter 7 the society up top is luxury and excess while the ones on the bottom suffer and the top looks down on the bottom for not turning into butterflies, something thats seemingly not even achievable through effort alone. Hope our mc, who still seems to have maintained some of her morals atleast, changes this society and more importantly reika for the better.
Thanks for the chapter