It's the year After Colony (AC) 195, a time when space colonies exist to ease Earth's population pressures. It's also a time of severe political repression; violent wars have left Earth under the control of an evil government called the United Earth Sphere Alliance. The alliance, which comes complete with its secert military society (OZ) and its behind-the-scenes corporate force (The Romefeller Foundation), is extending its iron-fisted control into space, seeking to eliminate all opposition, even in the freedom-loving space colonies.

One of the principal means of force is the mobile suit, a giant, human-shaped battle machine with a pilot inside. Typically, moblie suits are hundreds of feet tall and capable of space flight. Each also carries immense firepower.

After decades of losing ground, scientists from space colonies devise a last-ditch plan: the development of five superior mobile suits, called Gundams, to battle the Earth Alliance forces. The Gundams, so named because they make use of a superior metal alloy called Gundanium, are to be sent to Earth to battle the Alliance's own machines.

Five young men, each only 15 years old, are chosen to pilot the Gundam suits. Each colony's team of scientists supplies one of the gundam suits, along with its pilot. Each suit has its own design and capabilites. The plot, called "Operation Meteor," calls for the pilots to bring the suits to Earth in secrecy and work independently of each other, causing as much damage and wreaking as much havoc as possible. But of course, things never go exactly to plan.