When one space colony declared its independence from the Earth Federation, the devastating 7th Space War, an all-out war between Earth and space, resulted. The Federation responded to the Space Revolutionary Army with mobile suits, called Gundams. However, the Space Revolutionary forces played their trump card and dropped hundreds of space colonies onto the Earth, plunging the planet into a seven-year-long nuclear winter. The Federation collapsed, but the Space Revolutionary Army was unable to invade the Earth in the aftermath of the colony drop. Fifteen years have passed. The year is now After War 0015, and a New Federation has sprung up on Earth to restore order. In space, the colonial leaders have been rebuilding their own forces as well. By chance, fifteen-year-old Garrod Ran has discovered an old Federation mobile suit, the Gundam X, and now he uses it to help out the Vulture ship Freeden in its struggle to keep the powers that be from repeating the mistakes of the past.

During the school's spring break, Kyouya "Kyoro" Shinomiya has once again been kidnapped. Upon release, he finds himself in the GJ Club room, together with his captors, the cute GJ club members. At first glance, Kyoro does not see anything out of the ordinary in the club room, but as he gazes out of the window, he realizes that they are no longer in Japan but in New York!

In the kingdom of Forland, a coup d'etat occurs which leads to the death of the King. In the last moments of his life, the King sends his second child, Princess Alita Forland to escape. Unfortunately, while fleeing, a life and death situation between Alita and the bloodthirsty bounty hunter Falis causes the two of them to switch bodies. Desperate for the safety of her Kingdom, Alita begs Falis to return and protect the Kingdom, offering herself as collateral. After a swift beating on the rebel forces, Falis resumes the title of Princess of Forland, leading to the birth of the most savage princess in their land, the "Murder Princess."

Sometime in the distant future, mankind is forced to live in domed cities while the rest of the world is left to recover from years of environmental hardships. In the Siberian Dome-polis, professional gamer Gainer Sanga and mercenary Gain Bijou commandeer an Overman and lead a mass exodus out of the city.