It's the highlight of GBN's anniversary event, the "Gunpla Battle One-Day Battle Royal"! Participants are selected from the Divers who played most passionately this season, and they're fighting in machines randomly assigned mainly from those Gunpla ranked highest by all Divers in the Great Gunpla Ballot! Now the final round is about to begin, with the tough fighters who've won their respective blocks! There, an unpredictable, super special, never-seen-before Gunpla dream battle will... START!!!

The story focuses and revolves around the 108th Guard Squad, stationed in Aomori. A poorly equipped unit with very little military standing, it is often viewed as a 'reject camp' for pilots not making the grade for the elite units based in Hokkaido. The apparent helpless nature of this force is hardly a deterrent for the encroaching enemy armies, ever closing in on both the 108th and the rest of the empire. The young pilots of the 108th, who had dreamed on returning home, are plunged forcefully and unwillingly into a war.

When a young boy called Hiro finds what appears to be a broken lighter in an empty field, it changes his life forever. This lighter is actually the Gold Lightan, a robot that fell to Earth from the Robot Dimension. When called upon to defend the Earth from Ivalda the Great's evil robots, Gold Lightan transforms into a giant super robot, known as the Golden Warrior. Gold Lightan joins forces with Hiro's and his gang, the One Pack Rangers to protect the Earth from the evil schemes of Ivalda the Great and his armored forces.

In the distant future, a majority of humans have left the Earth, and the Galactic Alliance of Humanity is founded to guide exploration and ensure the prosperity of mankind. However, a significant threat arises in the form of strange creatures called Hideauze, resulting in an interstellar war to prevent humanity's extinction. Armed with Chamber, an autonomous robot, 16-year-old lieutenant Ledo of the Galactic Alliance joins the battle against the monsters. In an unfortunate turn of events, Ledo loses control during the battle and is cast out to the far reaches of space, crash-landing on a waterlogged Earth. On the blue planet, Gargantia—a large fleet of scavenger ships—comes across Chamber and retrieves it from the ocean, thinking they have salvaged something of value. Mistaking their actions for hostility, Ledo sneaks aboard and takes a young messenger girl named Amy hostage, only to realize that the residents of Gargantia are not as dangerous as he had believed. Faced with uncertainty, and unable to communicate with his comrades in space, Ledo attempts to get his bearings and acclimate to a new lifestyle. But his peaceful days are about to be short-lived, as there is more to this ocean-covered planet than meets the eye.