Kero 0: Shuppatsu da yo! Zenin Shuugou!

On the day the Keroro Platoon is supposed to depart Keron for its invasion of Earth, Giroro and Zeroro are already waiting at the space station while Keroro is nowhere to be seen. Their routine departure is interrupted when hostile aliens attack the station, throwing the mission into chaos before it has even begun.

With the station under assault and time running out, the future invaders of Earth must first survive trouble on their own home turf. The crisis reveals how Keroro, Giroro, Zeroro, Tamama, and Kururu come together before the misfit platoon ever sets foot on Pekopon.