Later, He Became A Royal Healer - Chapter 75 - Can't carry you.

In a romance novel called “The Secret Lovers of the Academy” the male lead would often torment his fiancée–but wait, why did she cross into this world to become his fiancée, the villainess, instead of the heroine?

Louise Sweeney found the perfect solution to escape the misfortune of being the villainess: “Your Highness, I just want to tell you that we don’t have to be tied with our engagement. We weren’t even officially engaged, right?”

But what was wrong with the male lead’s reaction? To her suggestion, he replied “But our engagement wasn’t false, don’t you agree?”

The mentally disabled 13 year old daughter of the Ye family, one day re-births! She rules over the Omnipotent God’s Cauldron, she possesses a spirit cultivation space. She’s no longer the good-for-nothing, abandoned girl who everyone bullies whenever they see her! With her incomparable poisons, even miracle doctors have to move to the side.

Spirit beasts beg for contracts, but too bad, even the God of Beasts have to call her Boss. Scum father, you dare to abandon your wife and daughter, she will surely make him destitute and homeless. People of the world, you dare to bully her, to insult her, she will definitely pay them back a hundredfold.

Reborn again into the world, she returns as a sovereign, but who knew she would attract the nefarious-blood-thirsty-demon him. He’s definitely the sly emperor who doesn’t hesitate to kill and cut down anyone, but he transforms into a harmless foolishly cute prisoner prince of an enemy country……

- Description from novelupdates

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.

She was reborn in the 1970s, when there were no mobile phones or TVs, people lived in poverty and marriages were arranged by families. He, the wealthy and powerful head of the regiment, who governed the local army, helped her join the army so that her family would no longer be bullied and could live a good life. And Suddenly, he proposed marraiage to her...