Mitou Shoukan://Blood-Sign - Volume 9, Prologue

In a modern world where cultivators need a place to cultivate or vent their boredom, there are private businesses that set up instance dungeons with the aid of technology and cultivation magic to enable cultivators to train and commoners to experience the life of cultivation. They are called dungeon suppliers.
Xie Jin's one and only dream was to be a dungeon supplier and when his only relative passed away, the relative's inheritance gave him a plot of land and surprisingly, a 'System' Module which the relative had previously used.
With the help of the system, Xie Jin decided to pursue his dream of becoming the number one dungeon supplier.

Vergil, a 21-year-old young man, leads an apparently simple life in a somewhat troubled world. His family is also simple—although his father is no longer alive, his mother has always been by his side, despite being a bit... aggressive. But that's not so unusual nowadays, right?Everything changes drastically when Vergil, after an unexpected death, awakens as a demon. To his surprise, he discovers that he has accidentally married beautiful Pure-Blood demonesses.Now, he will discover how the world really works from a Demon's perspective.

A world filled with heroes with superpowers. A world attacked by calamity fiends. A modern world filled with wonders and dangers.

Shi Xiaobai, a child from normal Earth, walked into such a world, proclaiming to be its king. But at the first signs of danger, he is forced to make a choice, one which he cannot refuse for time would repeat, making him face the choice again.

He is not humble nor is he modest, but neither is he delusional. Yet, the Absolute Choice seems to make fun of him. Will the joke be on him or will he laugh at his opponents? There will be many watching his escapades, and there will be some joining him in his adventures.

To see through the world and to grasp its truth, that is the destiny of the King.

- 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.