Elf Tensei Kara no Cheat Kenkoku-ki - Chapter 8Book 5: -2: The Empire’s Weakness

I’ve entered a hidden route in a failed game.And now, I have to become a false prophet.There’s no other choice.Since it’s come to this, I’ll become the greatest false prophet on the continent.

MC (female protagonist) dies in a plane crash and wakes up in the body of a beautiful but corrupt and lascivious prime minister in ancient times, Zhang Qinglian. As circumstances decree, he (she) cannot reveal that the original owner’s soul is gone else calamity might occur. So he (she) decides to walk a righteous path, determined to help the lovely but simple little emperor rule the country. Not backing down after facing torture, not losing courage, destroying rebellions and facing off with scheming princes.

- Description from Novelupdates

What is it like to be a prison guard in another world? Thieves, pirates, assassins, con artists, terrorists… Werewolves, vampires, witches, necromancers, succubi…This is the Iron Rose Prison, where the most dangerous witches in the world are gathered.“I will make this the best model prison in the world!”said a prison guard who had been transported to another world.“Warden, someone has escaped again!”“Bring them back and put them in solitary confinement.”Today, is also a peaceful day on the Rose Prison.Warden: “I’m just trying to run my prison properly, how did I become a big shot in this world?”

The world was once at war with 10 alternate worlds. This was known as the Concept War and our world won 60 years ago. All of this was concealed so no normal people are aware of this fact in the current time.

After the death of his grandfather, the high-school student Sayama Mikoto is suddenly summoned by the giant corporation IAI. He learns this world is headed for destruction due to the acceleration of the Minus Concepts. To prevent this, negotiations must be undertaken with the survivors of the other parallel worlds so their 10 concepts can be released.

And so Sayama is caught up in the final battle to clean up after the Concept War which left behind so much enmity.