Set before the main Keroro Gunsou series, this special serves as its episode zero and was screened in theaters together with the fourth Keroro Gunsou movie. On the day Keroro's battalion is due to leave Planet Keron for Earth, a hostile alien race attacks the Keron space station. Giroro and Zeroro, who later goes by Dororo, are there waiting for Keroro to show up. The result mixes comedy and action with some mecha flavor.