In the fantastical world of Flonyard, an alternate Earth inhabited by human-animal hybrids, the Republic of Biscotti faces a dire threat from the feline Galette Leo Knights. To protect her people, Princess Millhiore calls upon a champion from another world. Enter Cinque Izumi, an ordinary Earth junior high student, who wields the sacred Palladion to defend Biscotti in a war that resembles a sports competition more than a battle. Despite his success, Cinque learns he cannot return home, bound to serve as Biscotti's hero until a way back is found. Determined scientists strive to reunite Cinque with his world, but for now, he remains by Princess Millhiore's side, fighting for his newfound home.