Two worlds, each invisible to one another, collided a century ago. The twin planets, Gaia and Aether, had once harmoniously shared an orbit around the sun for billions of years without having any awareness of each other. Gaia was a colossus of a planet, two times the size of Aether yet somehow falling behind in terms of magic usage, and thus developed a system known as magic technology. On the other hand, the people of Aether, blessed with the natural capacity to convert aether into mana had advanced so far into the realm of magic that they can manipulate nature itself, though they have made violating it forbidden.

A century ago, a calamity occured: a rift between the two worlds began appearing, sucking both in a magical vortex--a phenomenon said to have already occured once, a million years ago. According to scholars, Gaia and Aether were once a single world, until the first vortex occured, an anomaly that split the two worlds apart. Now, as if the power that had divorced the two worlds had waned, another vortex appeared, one that joined the two together again.

It was chaos at first, as sovereign territories collided and new nations formed. The chaos lasted for a decade before diplomacy won over supremacy, and alliances formed, making stronger and more powerful nations. In The Republic of Branch, allied to the Kingdom of Cloud, an agency of eccentrics was formed to combat the growing tension between the two allied sovereignity.

This is the story of a Gaian police officer and an Aetherean mage.