Maybe a Fake Gintama - Chapter 24: Children Don’t Need to Know [This Way and That Way and Every Other Way]!

Mythical Abode Mountain, Cloud’s End Cliff, the most dangerous of Azure Cloud Continent’s four deadly areas. Cloud’s End Cliff’s base is known as the Grim Reaper’s Cemetery.

At Elysia's first meeting with the crown prince, her future fiance ended up punching him. In this way, she violated her first law of survival.

Elysia's three rules of survival - First, Stay away from the main couple of Adam and Eve and make sure they end up together. Second, never fall in love with anyone and keep yourself safe. Third, no matter what happens, make sure you are never caught in any act. Only then will Elysia be able to survive past her death on her 18th birthday.

Ever since her birth, Elysia Raffle knew a few secrets of this world. First, the world she had been born in was a book and Elysia was the villainess in that book. She was destined to be slain by Adam on her 18th birthday and the day of their marriage.

Elysia needed to keep a distance from the main couple to avoid that fate. But how did she do it when she was engaged with one of the main parties and the other refused to leave her alone?

Now Elysia needed to do everything possible in her power to ensure that her engagement with the crown prince was broken and the main couple ends up together.

But it was easier said than done.

Liu Duo was a young girl whose grandmother sold her to four brothers with the intent to be a bride. Unwilling, she ran away the following night, only to fall unconscious while trying to get away. Unexpectedly, however, she was reborn with the spirit of a 25 year old woman, also named Liu Duo.

- Description from Novelupdates

In the era of universal mechas, people can go to the endless abyss, collect materials, strengthen and forge their own mechas, and master the power of destroying the world.

Jiang Chen traveled through time and awakened his talent [Immortal Unarmed]. Once the mecha is broken, he can permanently absorb its power and receive multiple bonuses.

…

At the bottom of the abyss, when the Old Demon God finally broke the Titan mecha with great effort, a hand stretched out from the fragments and held down its head.

“Congratulations, you have unlocked my limiter.”

- Description from novelbuddy