Mythical Beasts: The Useless Lady Is a Genius! - Chapter 21

When an S-class elite assassin-raised captain of a special ops suicide squad comes home from a high-stakes Africa mission, he finds himself offered something that could potentially set him up for life- a curious assignment that he could use to finally exit his days of war and slaughter.

Then placed into a high-school setting, Lin Yi is tasked by the chairman of a top-tier multi-billion company with bodyguard duty for non-other than his own daughter, a certain little Miss of said high-school.

His enemies, once ranging from drug lords, mafia bosses, political figures, and national leaders, are soon replaced with spoiled kids who happen to have rich papas and mamas, and Lin Yi finds his intense expertise and high-threat skillset misused, and very underwhelmed…

But he does get a harem cast as diverse as his old enemies, so Lin Yi decides that, for the sake of messing around with girls as an invincible entity in a down-leveled environment, leaving his bloody and death-filled war days behind is something he’d definitely want to strive for.

- Description from Novelupdates

Reborn as a sword, he lived for hundreds of years, and then he occupied the body of a 15-year-old prince.

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.

“Compared to our time, the current generation just aren’t as reliable” they said, “Still, isn’t he the son of the Hero?” How annoying.

It’s been over ten years since the battle between mankind and the demons ended. The children of the heroes who saved the world are all grown up.

One of them, Earth, was a talented man, and everyone expected him to succeed his father as a warrior and defend his country, but Earth was always wary of his father’s title.

One day, Earth is shocked to find his father’s sword, which was used to overthrow the Demon King, sealed in his family’s mansion.

Because trapped within was the ghost of the Great Demon King who was unable to pass on and continued to roam the world.

For some reason, only he could see the spirit of the Demon King, and the Demon King possessed him through the sword.

Every day, forced to coexist with the spirit of the Demon King, they live a strange shared life, when the Demon King whispers to Earth on a whim.

“I have a grudge against your father. If you want to get back at your father and the world, I’ll train you. I’m free.”

Earth receives special personal guidance from the Demon King just to get back at his parents and the world.

Then, in the coming days. The hero’s parents, the heroes of the past, the first love, the princess childhood friend, the geniuses of the era, and the world will tremble.