The latest invasion plan goes slightly off course when Fuyuki is accidentally hit with a de-aging ray, turning him into the rambunctious little kid he used to be. But he`s in good company, as Keroro, Giroro, and Dororo turn themselves into half-pint sized versions of themselves, too. They all get along until Li`l Fuyuki challenges Li`l Keroro for the position of platoon commander.