Across has a new rival in its quest for world domination — a Puchuu invasion force from the planet Mars. As the city suffers from a torrential deoluge of rain, only one woman remains energetic and foolish enough to brave the weather and save the world from the Martian invasion — Excel Excel. Armed with her emergency food supply Menchi, Excel may well be the only one able to withstand the Puchuu’s greatest weapon — their overwhelming cuteness…

When Kabapu sends Watanabe and his colleagues to investigate the sewers surrounding the Across base, Ilpalazzo dispatches Excel and Hyatt to deal with the intruders. However, even as the duo familiarise themselves with the Across security system, they discover a far more sinister breed of intruders lurking in the sewers- an army of Puchuus led by the nefarious Puchuu Queen! Will Excel and the others be able to stand against this overwhelming cute force of evil?

Having decided that his employees need some additional training, Kabapu sends Watanabe and the others to train under Purin, a detective who can turn from a tough-as-nails old-timer into a cute girl quite literally at the drop of a hat! And whilst they tag along for Purin’s latest case, Excel has some problem solving of her own to do when Hyatt is taken hostage by a pair of burglars.

On a mission to investigate the situation in America, Excel and Hyatt run into a band of street thugs… and a communication problem. Fortunately, they get some help from Sandora, the son of Excel’s late friend Pedro, who is working as a cel animator to support his mother. But it seems these cels are being hoarded by an evil gangster, who quickly gets a hard lesson in the rules of cartoon heroics by an outraged Excel.

Having finally gotten the hint from ACROSS that he should hurry up the whole invasion thing, Ilpalazzo orders Hyatt to perform final preparations for the conquest of the city of "F", and orders the bungling Excel to keep her nose out of it. Excel has no time to be dejected, though: the Puchuus have returned, and she and Hyatt must help a band of freedom fighters thwart the machinations of an evil conqueror and his really big spaceship! But even after our favorite ACROSS agents defeat the invaders and destroy their ship, the city of "F" gets squashed by the falling debris. Well, them’s the breaks…

Fed up with the insanity, Koshi Rikdo finally insists that the animation and writing crew finish the freaking series already. So, the Safety Assurance Agency locks horns with ACROSS, Excel tracks down Ilpalazzo and beats some sense into him, Watanabe finally realizes the truth about Hyatt, and the series finally comes to an end… or does it?