Upon returning to Earth, Lamune has no memory of his thrilling escapades on the Hara-Hara planet and Doki-Doki galaxy due to amnesia. Meanwhile, Don Harumage's spirit is unintentionally revived when Gobuhriki's remains are discovered on Earth. In order to construct a strong combat vehicle, Cocoa utilizes all available resources in Tokyo. In an attempt to prevent the creation of the new Gobuhriki, which could result in the complete annihilation of Earth, Milk and Leska embark on a mission to find Lamune and Da Cider.