Prelude

In the 1800s, archeologists found the true history of the Earth. The Age of Monsters.

From what they've interpreted, it was obvious that magic and monsters had ruled the Earth long ago. Majestic skeletons that had dissolved into thin air right after humans dug them out from the soil were found in the latter years, which only confirmed the theory that there was once a power beyond science. 

No one knew how these monsters disappeared from the Earth. But they always lived in fear, for the monsters could return at any moment. 

And… in 2000, they did. 

As the years passed by, people figured out how these monsters arrived. 

The archeologists believed that due to a particular phenomenon, magic on Earth had been dying near the end of the Age of Monsters. But in recent years, due to a paranormal occurrence of a Human mind linking with the Monsters, they had found a way to return to Earth's surface once more. 

The theory is that these Monsters were not dead. 

They had existed for thousands of years in a magical plane that was not the Earth itself. 

Now, Monsters seek to rule the Earth once again. With the human mind linking with these titanic beasts, the linked humans are driven by the desire to serve these Monsters as their masters – at least that's what the records in the Monster Hunter Society said. 

As long as the linked human lives, the Monsters could break into the human plain through the magical plane of existence. So, these Humans act as the summoners for these monsters. 

To avoid the catastrophe brought upon the cities, people dedicated to saving humanity from the Monsters created Monster Hunter Society. 

What's their main target? 

Finding the linked humans and putting an end to them so Monsters could not retake the Earth from humans.