At a party in Klein Sandman's castle a woman wearing a purple dress leaves the party, taking off her disguise to show it is really Eiji Shigure. Luna Gusuku and Mizuki Tachibana are watching him from the monitors and set the alarm off to capture him. Eiji escapes into the depths of the castle, stumbles across a giant robot and Toga Tenkuji steps out. Eiji states he is in the castle looking for his sister, Ayaka. The castle starts shaking and Eiji falls through a crack in the ground under the castle. Back at the party Sandman appears, announcing that Earth is currently under attack from aliens. The aliens start attacking Earth, and the units inside Sandman's castle launch a counterattack. Eiji finds himself inside a plane that is to be launched in the counterattack, and he has to fight in the air battle against the aliens. As the battle looks hopeless, the mecha Gran Kaiser, piloted by Toga appears. During the battle, Luna contacts Eiji to tell him to let her control the plane. A full Zeravire alien appears, and the Gran Kaiser's attacks prove ineffective. The Grand Divas combine with the Gran Kaiser to create the God Gravion.