After the catastrophe that destroyed their continent, the inhabitants of Mu have adapted to living in the ocean, in cities covered by huge domes.
Osper wins the battle and after being defeated, Drome destroys the dome in revenge and escapes to Earth.
After being cornered, Drome activates the ultimate weapon to destroy the Earth, and engages Osper on the place be prepared for a final battle.
In addition, the whereabouts of film masters for all episodes of the series were unknown until 2022 as Nihon Terebi Dōga had dissolved.
Opser was found and was subsequently restored by the efforts of a crowd fund on Camp Fire.
Horde of Osper Poisonous Moths" (戦え！オスパー毒蛾の大群) was found in an abandoned warehouse and given a limited release on DVD.
As of 2023, a copy of the DVD is now on view to the public at the National Diet[4] On the 17th of May, 2023, the 41st episode of the series suddenly appeared in full on YouTube, uploaded by a user named "kamoogy mckinnable", The user is suspected to be either one of the supporters who had been given a DVD by Kokuei upon the limited screening of the episode or that the episode had been leaked before May 17th on various Japanese video-sharing sites and message boards beforehand and had just been re-uploaded on YouTube by said user.