Set in Ranstar, a world modeled on Japan's Sengoku era, this short special puts the Keroro Platoon up against the Vipers, with every character dressed in period fashion. Running about 14 minutes, it was shown in theaters alongside the third Keroro Gunsou film and serves as a prequel to the Mushakero storyline in the fifth season of the main series, mixing action, comedy and mecha.