In the near future, chaebols will replace the political power, and wars will continue in order to compete for interests. The Igodra Company discovered the remains of aliens and their equipment in the near-Earth universe - code-named [Urd], and then discovered a mysterious particle that humans have never understood, called the Delta particle. The appearance of delta particles has broken the balance of human forces. Relying on the unique delta technology, Ygodra Corporation has developed a powerful extensible tactical exoskeleton——Aita, whose military strength has reached an absolute advantage over the chaebol. In order to consolidate its interests, Ygodra Corporation built a huge circular orbital base - Gray City above the equator, and carried strategic weapons on it. The existence of Gray City threatens the interests of other chaebols, and they unite to form the "Human Alliance" to attack the Ygodra Corporation. In the end, the Human Alliance won the war at a heavy cost, and the Gr...