Sgt. Frog Episode 13 English Dubbed >Dororo and Koyuki are taken prisoner by a member of the Vipers, natural enemies of the Keronians. The platoon goes to the rescue only to fail miserably for the lack of a fifth member. Keroro comes clean about breaking Dororo's music box a long time ago prompting Dororo to forgive him and help the platoon defeat Viper. At the end, Dororo realizes how painful was to remember his box and refuses to join them again.