Shinwa Densetsu no Eiyuu no Isekaitan - Volume 3, Chapter 1 – A New Problem, Part 1

Qin An was a former senior grim reaper who retired after serving the underworld for thousands of years. Because of his outstanding service and had enough merits, he was given a chance to become a human and unexpectedly transmigrated to the Interstellar era. But, how can he live his retirement days when has no money and everything? So, Qin An entered a reality talent show for idols and became an existence that everyone admires to.

Through a mysterious portal, Chen Jin arrived at this strange place – a post-apocalyptic world where civilization had been destroyed.

Consequently, he found –

A piece of metal scrap
A robot trash collector
A battleground
A city
A ton and more of gold
A copy of high-tech documents
A…
In short, Chen Jin found a planet.

- Description from Novelupdates

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.