Things don't always appear as they seem.~

Thirty years ago a strange phenomenon called a "spacequake" devastated the center of Eurasia, claiming the lives of at least 150 million people. Since then, smaller spacequakes plague the world on an irregular basis. A spacequake is when a spirit approaches and lands on Earth, it causes a spacequake. Even if they don't intend to, a big part of the city they land in, usually gets destroyed. Which makes them very dangerous and highly unpredictable even if they appear 'harmless'.

Because of these spacequakes and Spirits, DEM industries were formed including the AST, or the Anti-Spirit Team which is one of it's branches. The DEM is one of the largest cooperations in the world and due to their enthusiasm in hunting down Spirits, they are considered economic rivals with Ratatoskr whom Kotori is affiliated with. The Anti-Spirit Team is a special unit within the Japan Ground Self-Defense Force (Japan's army) that is designed to suppress and ultimately eliminate the threat posed by Spirits. They utilize Combat Realizer units (CR Units) layered on top of combat wiring suits to enhance normal human capabilities while providing offensive and defensive combat capabilities. The CR Units are based upon equipment that utilizes technology recovered by humans after the original spacequake. The cities are now also prepared before each spacequake, having safe centers for every person in the area to take cover in, since the quakes have been happening more oftenly not and the Government would like to not have a repeat of the first spacequake. 

 

Spirits are extraterrestrial beings from a different dimension whose arrival is usually preceded by a spacequake. These spacequakes are usually involuntary, but they can also cause spacequakes voluntarily, as Kurumi, Kotori and Miku have shown. Each Spirit has a numerical kanji in their name. They also each possess an Astral Dress as well as an Angel, which are respectively named after the Divine Names of the Sephirot of the Kabbalistic Tree of life corresponding to the numerical kanji in their names, and the archangelsgoverning the corresponding Sephirot. Each Spirit has a unique ability, and each displays different levels of knowledge about Earth. 

 

Ratatoskr is an organization created for the purpose of resolving the issues of Spirits and the spacequakes through peaceful means which would naturally make them rivals of the AST/DEM because they try to beat the AST to the Spirits first, in hopes of trying to peacefully learn more about them and understand them. It has also been stated that the organization was created for Shido's sake as he has the means to peacefully seal a spirit's powers. Ratatoskr's command center is located upon the airshipFraxinus. The headquarters for Ratatoskr is at an undisclosed location which houses all of the records for Ratatoskr as well as being the location for high-ranking members of Ratatoskr and the Rounds to operate from.