You smell it in the air and feel it in your bones. There's even a certain hop in your walk. Yes, indeed, summertime is finally here! But Keroro and the Hinata clan seem too busy to take notice of a little war of the worlds. As temperatures rise in the heat of battle, there's one cure for this group of hot heads: Soaking in a cool pool! Alas, there's just a little problem of shrinkage, and we don't mean from an alien member. So tune into your cosmic radio and broadcast to everyone you know--that giant sucking sound you hear is the latest in Keroro's new line of toys! But the question is: Will we all make it through this adventure without croaking?