The Labyrinth Chronicles of a Certain Kidney-Deficient Mage

Transmigrate to a world of magic, shoot goblins, blast greater demons, forge peace with nuclear weapons, and create a new age with magical technology.

A transmigrator, naturally, has to change the world. A very end-of-the-world, punk labyrinth adventure.

The world is doomed to be destroyed anyway, so why go out of your way to make it happen?

Ever since the protagonist's brain stopped working properly, he's become a real jerk.

The protagonist is an ordinary engineering office drone. No abuse.