Everything began with the first 'Gate' that appeared in the United States.

A mysterious dimensional rift appeared in the middle of a city, and from within, 'Monsters'—creatures humanity had never encountered before—emerged.

The monsters from the initial Gates were at a level that could be suppressed with modern firearms and armored forces. Nations around the world perceived this as a new form of biological disaster and controlled the situation relatively easily by mobilizing their militaries.

However, that was only the beginning.

As time passed, the Gates grew larger, and the monsters that emerged became incomparably more powerful. As if testing human response capabilities, the monsters evolved into entities with high intelligence, overwhelming physical abilities, and special supernatural powers.

Extermination became difficult with existing weaponry, only resulting in increasing casualties. Eventually, Gates began to appear simultaneously across the globe, spanning Europe, Asia, Africa, and South America beyond the United States.

Human civilization faced the greatest crisis of extinction in history.

In this desperate situation, major nations set aside their political conflicts and established a joint research institution.

The final plan they pursued for humanity:

Artificial Ability Injection Project (AAIP)

This was a project to artificially awaken supernatural powers in human bodies using unknown energy extracted from monster corpses and special substances found inside the Gates.

The experimental subjects were mostly special forces members and soldiers from various countries.

However, humans were not originally designed to accept such power. Numerous subjects lost their lives to physical collapse, mental contamination, and berserk phenomena, and the success rate was extremely low.

Nevertheless, humanity had no luxury to mourn the failures.

Project leaders defined the sacrifices as an 'inevitable cost for human survival,' and after countless sacrifices, superhumans who could stably use their abilities finally began to be born.

They were no longer mere soldiers.

They were reborn as living strategic weapons created to hunt monsters.