Ah, yes...The only thing to do when you enter a parallel world where sex doesn't exist? You create it and spread the word, becoming an evangelist of sex.
Interestingly it seems to be all part of a big conspiracy though. The bigwigs controlling knowledge of sex and keeping it from the 'lower class', huh.
A bit of a downer ending though. So...The rest of them were just disposed of, huh. And rather than lead a revolution of sex knowledge or anything like that, she falls victim to the government(?)'s scheme and just becomes a baby-making machine, so to speak.
Reminds me of a classic sci-fi flick called "Logan's Run", where, the masses are *koff-koff* killed off when they reach the age of 30, while a select few (the society's rulers) stay alive way beyond that point.
Here's hoping that, in actuality, Ryouka-chan has not been "permanently mind-broken", and that she will sooner or later lead a successful uprising against the society's current leadership.
EDIT: And when said uprising is done, the overthrown former leaders should be subjected to ... what else ... "Death By Snu-Snu"! ★