Kill Me More Times, I'll Become Invincible - Chapter 20:

Wu Lai was an ordinary high school student. One day he was struck by a flash of lightning from a different world, and suddenly entered a fantastic world full of magic and swords. Since then, he started a totally new life. In this supernatural world, he had his ups and downs, experienced numerous battles, subdued powerful evil beasts, and fell in love with a belle. His nickname “Demon King” was remembered throughout the ages there.

Stay or return was a question. In the face of this choice, Wu Lai, with the nostalgia and gratefulness for the original world, finally chose to stay…

Here was the legend of “Demon King”…

- Description from Novelupdates

You shall become king—

Ruling over all “serpents” in the world…

Become the man who bears the brunt of dragonkind’s fear and hatred.

A modern era when humanity is threatened by attacks from giant dragons flying from beyond the sky.

Controlling “leviathans”—serpentine spiritual beings created through magic—humanity is locked in a protracted war of resistance against the dragons.

Fortunately, there exist witches known as “magi”—battle maidens of salvation who formed covenants with “serpents” in order to combat dragons.

Nicknamed Hal, the young man called Haruga Haruomi makes his living through facilitating the covenants of these girls.

At the (partially coercive) request of his childhood friend Asya, one of Europe’s top witches, Hal returns to Tokyo New Town after an absence of three years.

Accompanied by the beautiful Asya whose appearance rivaled a fairy’s, Hal is running all over the place to secure his base of operations and taking care of matters related to school transfer when the elite dragon Soth suddenly attacks—!?

Life has been breathed into a brand new myth between dragons and dragonslayers.

A grand opening to the “birth” of a top-class battle epic!

Betrayed by those he empowered. Slain at the peak of his reign. Reborn into a world unworthy of him.Tian Mo was once a supreme cultivator, a dark sovereign who ruled with absolute might and terrifying intellect. After a million years of conquest, his closest allies turned on him, stripping him of everything. But fate offered no rest. Reincarnated into modern-day Earth, he awakens in a weak mortal body—yet his memories, ambition, and ruthlessness remain untouched.In this strange new world of technology and fragile peace, Tian Mo finds new prey. With the Primordial Chaos Demonic Evil Physique and the forbidden Divine Sins Emperor Technique, he begins building his empire from the shadows. He manipulates the system, devours the corrupt, and topples the powerful—not out of justice, but vengeance... and the endless hunger for power.There are no heroes in this tale. Only a monster reborn—and the world that will burn beneath his feet.

Forge unparalleled mechs with the ambition of old age, and use the galaxy as a knife to smash the edge of the empire.

His name is Ji Xinghe. When he was 65 years old, he went to Alien Battlefield to avenge his son.

The old man is standing on the ground, his ambition is a thousand miles away, the old man wears armor, and fights to the galaxy, the old man drags his sword, it is not for glory.

- Description from novelbuddy