Elf Tensei Kara no Cheat Kenkoku-ki - Chapter 10Book 4: -4: Compromise

Xu Mo, a modern high school student was sent back in time to Jing Kingdom and found herself trapped inside of the body of a princess with the same name.

She had barely recovered when she learned of an unparalleled fiancé and in a daze, they got married. Then the stunning genius physician who normally does not pay attention clamoured to marry her. After that, there was a cold general, a flirtatious lord, a tsundere young master……

As it turns out, this was a male-dominated dynasty. Because the female population was sparse, the entire nation shared wives regardless of rank or nobility. Is it feasible for someone who wants to maintain monogamy in this dynasty?

- Description from Novelupdates

The older sister flees from her wedding to be with her lover, and her younger sister is forced to take her place in marrying a very powerful man.

—

As luck would have it, she ends up transmigrating into the body of that younger sister.

Although the man that she weds is very powerful, he’s the irredeemable final villain.

All villains are doomed to a bleak ending. And, as this villain’s wife, she’s afraid that her ending won’t be good either.

Fortunately, the older sister had gone back in time after having experienced a lifetime of suffering. This prodigal daughter returns to the turning point of her life. Pointing at her younger sister, she demands for her younger sister to hand over her husband.

Looking at this beautifully crying older sister, Ye Zhen swiftly yields and says, “Older sister, don’t worry. I haven’t even done anything with brother-in-law!”

—

To her shock, she later discovers that she’s pregnant.

With tears in her eyes, her older sister says, “Didn’t you say that nothing happened between the two of you?”

—

Ye Zhen looks at the great villain that doggedly pursues her. She is utterly and totally doomed.

—

There’s a great villain lying next to her, and she’s pregnant with a mini villain. How’s she suppose to survive?!

—

Later on, as Ye Zhen watches the great villain putting the baby down and changing the diaper, she sighs. “There’s nothing that can be done. I’ve already missed the golden opportunity to turn things around. How can I leave now?”

- Description from novelupdates

Humans across the world ended up joining a “Demon Kings and Heroes game”.

Several billion people were set down upon another world to act as “Demon Kings” and “Heroes”. Everyone has to chose their starting races from the start.

Zhang Nu was set in the Demon King camp.

He discovered that he could see hidden information that no one else could.
[Slime Demon King]. Low grade demon king bloodline… Not recommended!
[Kobold Demon King]. Low grade demon king bloodline… Not recommended!
[Dark Elf Demon King]. Mid grade demon king bloodline… Can be selected!
[Bloody Giant Demon King]. High grade demon king bloodline… Recommended!
[Abyssal Dragon Demon King]. Strongest starting bloodline… Extremely recommended!

Bro, I mean, I'm just a tad handsome, a bit skillful, and slightly crafty, that's all! Why do you all have to make my life difficult? This incessant pestering isn't the answer, is it?What? You'll marry no one else but me? No...you...how could you? Without even asking for my consent?