This one-volume manga retells the opening of Dog Days: ordinary middle-schooler Cinque Izumi is summoned to Flonyard by Princess Millhiore of the Biscotti Republic to fight off an invasion from the feline Galette Lion Dominion. Cinque and Millhiore quickly discover a catch neither expected, that anyone pulled from Earth cannot go back, and the story follows Cinque settling into his role as Biscotti's new Hero while that problem stays unsolved in the background. It condenses the opening of the original television series into five chapters.