1999.

A meteor collision created a hole connecting Earth to anotherworld.

While Earth reeled in confusion, the Lemurian Federation, one of the two great powers in the otherworld, launched an invasion of Earth.

Struggling against the otherworld's magic, Earth, aided by the Astoria Kingdom—the other nation in that world—succeeded in developing a technology called "Sorcery."

The advent of sorcery led the war into a stalemate, and a truce was finally signed between Earth and the Lemurian Federation in 2002.

Fifty years later.

The Lemurian Federation and Earth's various nations somehow maintained a fragile balance, repeatedly toggling between ceasefires and renewed hostilities.

Amidst this delicate balance, a lone Japanese boy descended upon the border region between Astoria and Lemuria in the otherworld.

His name was Yuuki Mamoru.

Also known as Sir Dreadnought.

He was one of the 48 knights who upheld the Astoria Kingdom.