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

A mysterious dimensional rift emerged in the heart of a city, and from within, creatures humanity had never encountered—'Kaiju'—revealed themselves.

The Kaiju from the initial Gates were at a level that could be suppressed with modern firearms and armored forces alone. Nations worldwide perceived this as a new form of biological disaster and managed to control the situation relatively easily by mobilizing their militaries.

However, that was only the beginning.

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

Suppression became difficult with conventional weaponry, leading only to increased casualties. Eventually, Gates began to appear simultaneously across the globe—beyond America to Europe, Asia, Africa, and South America.

Human civilization faced the greatest crisis of extinction in history.

In this desperate situation, major world powers set aside political conflicts to establish a joint research institution.

Their final plan for humanity:

Artificial Ability Injection Project (AAIP)

This project aimed to artificially awaken supernatural powers in the human body using unknown energy extracted from Kaiju corpses and special substances discovered inside the Gates.

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

However, humans were not originally designed to withstand such power. Numerous subjects lost their lives to physical collapse, mental contamination, and berserk states, resulting in an extremely low success rate.

Nevertheless, humanity had no leisure to mourn the failures.

Project leaders defined the sacrifices as an 'inevitable cost for human survival,' and after countless losses, superhumans capable of using their abilities stably finally began to emerge.

They were no longer mere soldiers.

They were reborn as living strategic weapons, created solely to hunt Kaiju.