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

An unidentified dimensional rift emerged in the middle of a city, and from within, creatures humanity had never encountered before—'Kaiju'—showed themselves.

The Kaiju from the early Gates were manageable with modern firearms and armored forces. Nations viewed this as a new form of biological disaster and controlled the situation relatively easily by mobilizing their militaries.

But that was only the beginning.

As time passed, the Gates grew larger, and the Kaiju emerging from them 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.

Conventional weapons led only to mounting casualties with no successful exterminations. Eventually, Gates began appearing simultaneously across the globe—from Europe and Asia to Africa and South America.

Human civilization faced the greatest threat of extinction in its history.

In this desperate situation, the world's major 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 remains and special substances found inside the Gates.

Most test subjects were special forces operatives and soldiers from various nations.

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

Yet, humanity had no luxury to mourn the failures.

Project leaders defined the sacrifices as an 'inevitable cost for human survival,' and after numerous 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 for the sole purpose of hunting Kaiju.