Kaiju Maker in Another World - Chapter 20: A Letter from Home

The world changed the day that cracks appeared in the sky– suddenly monsters named『Demonic Beasts』appeared and began to rampage, attacking people.

Meanwhile, girls called『Magical Girls』began to appear to counter the demonic beasts. As they defeated the demonic beasts, gradually people’s lives gained a semblance of composure.

–but when there is light, there is also darkness.

In the corner of an alleyway, a boy who had been attacked by a demonic beast was dying. His voice begging for help did not reach anyone and his body refused to move.

「Boy. Do you want to be saved?」

Looking into the boy’s face, a black cat began to speak to him.

The boy nodded firmly to the devilishly sweet invitation, in response the black cat mocked him.

「Is that so—then I’ll【Haunt (Save)】you」

—on that day, a『Magical Girl』was born in a place that no-one knew.

『She』never laments, no matter what the future may bring.

It begins on the mountain.

With the glint of a knife, a flash of steel in the hands of a sworn brother. A betrayal.

Stabbed and pushed down the mountain, Zi Chen lied within the red-stained snow, left to die.

This is where it begins; he is given life by lightning,
baptized by thunder.

Those who had once betrayed him should all suffer in his cruel revenge.

- Description from Novelupdates

Vincent Strider was a gun for hire who made a living by killing whoever it was his clients wanted dead. But during one mission, he died in a fierce gunfight. However, death was not the end for him. Vincent found himself reincarnated in another world, facing a floating interface that flickered before his eyes.[Synchronizing Host!][Military System initializing.]Vincent found out that in this system he received, he can summon soldiers, tanks, aircrafts, and even warships! This is going to be exhilarating.

Carn wakes up from a vivid dream where he spent a thousand years as a gargoyle, guarding a demon lord's tomb.In this dream, he possessed supernatural powers, including the ability to teleport and instantly kill anyone within range who broke eye contact with him. Heroes, saintesses, adventurers, all fell before him.When he returns to his normal life, things take a strange turn. Carn realizes he still has the gargoyle’s powers, and the world he has woken up to seems different.But adjusting to the new reality is not the real issue. Carn brings back something nobody in this world has imagined. Not only he imports his powers to this alternate Earth, but he also carries over his gargoyle instinct and his hobby. He loves snapping human necks.Whether it's ordinary humans, explorers, super soldiers, cyborgs, mutated beasts, monsters, or mysterious entities from other dimensions, Carn eagerly anticipates snapping their necks, one neck at a time...In secret, of course.