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

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

The Kaiju from the early Gates were manageable enough to be suppressed with modern firearms and armored forces. Nations worldwide perceived this as a new form of biological disaster and mobilized their militaries to control the situation relatively easily.

However, 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 weaponry led to mounting casualties while making suppression difficult. Eventually, Gates began appearing simultaneously across the globe, spanning Europe, Asia, Africa, and South America.

Human civilization faced the greatest threat of extinction in its 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 human bodies 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. Numerous subjects lost their lives to physical collapse, mental contamination, and berserk phenomena, resulting in an extremely low success rate.

Nevertheless, humanity had no room to mourn the failures.

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