The Genius Assassin Who Takes it All - Chapter 187

The scum’s or villain’s long road of transformation was tentatively set to the world:
The abandonment of the educated youth’s wife (Completed)
The hidden marriage of the scum film emperor (Completed)
The best brother in the world (Completed)
The Phoenix male who destroy the bridge after crossing the river (Completed)
The treasonous general (Completed)
I’m an honest man (Completed)
To become the top scorer in the School of Agriculture (Completed)
The soft rice man’s self-cultivation (Completed)
The whole world is reborn (Completed)
I want to survive on a desert island (Completed)
The stallion male who has seized the opportunity (Completed)
The perverted self-salvation (Completed)
The spring of the loafer (Completed)
The misplaced life (Completed)
The miser career (Completed)
The ghost is out of feeling (Completed)
The Queen’s favorite husband (Completed)
The vicious girl with her godfather (Completed)
I want to be a good person (Completed)
I does not tear up the family (Completed)
The perverted common plant (Completed)
The Mary Sue’s men (Completed)
Every time I was reborn, someone wants to kill me (Completed)
The old people’s counterattack path (Completed)
The global evolution (Completed)
When I became a net red (Completed)
For you, good person (Completed)
His heart had white moonlight (Completed)

- Description from Novelupdates

Leon was once an ordinary man—until he died saving children and woke up in a new world as the last prince of the demon race. But his awakening comes with a cruel truth: the war is already over.The Demon King is dead. The once-mighty demon empire lies in ruins. And now, Leon stands amidst the ashes, surrounded by a handful of survivors teetering on the brink of extinction.Crowned Demon King by default, he holds the title—but there is no kingdom left to rule. The few remaining demons are barely surviving, hunted and outnumbered. Worse still, Leon, who once enjoyed the luxuries of modern technology, must now navigate a harsh world stuck in the Middle Ages.Can he pull the demon race out of their misery? Can he reclaim the power they once held? Or will history remember him as the last king of a fallen race?Follow Leon on his journey to rebuild, conquer, and defy fate itself.

In the 21st century, she was the talented leader of the hidden family clan, once she crossed over, she became the number one waste?

Skyler's story was typical. He was publicly labeled a waste with no future as a Light — awakened individuals capable of wielding elemental powers. He thought that would be the end of it. But no, apparently that was not the case.He was teleported to the 'Battle Royal' to fight, even though he had zero powers and his age and potential were 100% ineligible!To make matters worse, he was not even the protagonist or transmigrator! He was just a freaking side character destined to die young in the story! And his death served only one purpose — to bring his sister closer to the protagonist!What a pitiful ending, right?However, unbeknownst to all, he wasn't meant to die but to become the best in two other realms, and they had altered the fate of that powerful King. Yet, there was a tiny problem — he didn't remember how he became overpowered in his past.