Having grown a bit too comfortable with their lives on Pekopon, the Keroro Platoon has completely forgotten about their invasion and leads idyllic, repetitive lives on the blue planet... Until one day, when they suddenly get a broadcast from the Keronian Army! Apparently, since they haven't conquered if after all the time and money they spent, the army's given up and opened the Pekopon invasion mission to anyone willing, all with promises of luxurious benefits to whoever succeeds (a rise in the ranks! A pay boost! An all-expenses-paid vacation to the tropical planets of the Gamma system!)
Naturally, Keroro is incensed! This is his job, dang it, and he's not gonna let Pekopon get swiped out from under his lack of a nose! So, the Keroro Platoon and their allies band together as the Pekopon Defense Squad for the sake of protecting the planet from these unruly invaders (mostly so Keroro can get it later, but, that's not really important). The frog is back, and he's brought a whole bevy of space-faring, Gunpla-building, Earth-shattering antics with him!
But, halfway across Japan, another story unfolds. The rivaling Parere and Zemomo Platoons have both set their sights on conquering Earth, but upon learning that both have touched base for the conquest, their leaders' heated rivalry gets the better of them and they spend all their time sabotaging and trying to one-up each other. One such day, a scheme war of theirs goes awry and two young girls named Mimi and Ran and caught in the mix and turned into Keronians! Needing to cover up their cover getting blown from the army, Zemomo and Parere have the girls pose as stranded Keronians they found on Earth while trying to undo the transformation. As time passes and they come to bond with the girls and learn of their lonely home lives, however, they start to question if they really want to keep this invasion attempt up. These three platoons will cross paths sooner than they even know...
