Upon arriving on Earth, the Mysterians constructed a colossal dome underground near Mount Fuji. The dome allowed the Mysterians to live in a controlled climate and gave them a defensible base of operations outside of their space station. From the dome, the Mysterians deployed their robot monster Moguera to attack nearby villages in order to demonstrate their technological power. After Moguera was destroyed, the J.S.D.F. tracked down the location of the Mysterians' dome. The Mysterians revealed themselves and demanded to speak to five humans. The humans entered the dome and were greeted by the Mysterians' leader. He explained that his people merely desired to be granted a two-mile tract of land on Earth on which to live, and the ability to mate with Earth women and rebuild their population. The human representatives, not trusting the aliens, refused and left the dome, after which the J.S.D.F. opened fire on the dome. The dome annihilated the J.S.D.F.'s forces with its death rays and Mysterian UFOs that it launched from its hangar. From within the Dome, the Mysterians began to up their demands, insisting that the humans give them larger and larger tracts of land to inhabit.
Later, Ryōichi Shiraishi, the human scientist that had been living in the Mysterians' dome, broadcast messages to humanity's leaders, urging them to grant the Mysterians' requests. Still believing the Mysterians' intentions were more sinister than what they claimed, the nations of the Earth formed a military organization called the Earth Defense Force, which constructed two powerful VTOL aircraft, the α (Alpha) and β (Beta). The Alpha and Beta assaulted the dome with their electron guns, but were unable to damage it. The Mysterians retaliated by firing death rays from the dome, which destroyed the Beta and forced the Alpha to retreat. Their attack repulsed, the EDF began work on a new weapon: gigantic mobile ray guns dubbed Markalite Cannons. While the EDF mounted a final assault on the Mysterian Dome with their new weapons, Joji Atsumi infiltrated the dome to rescue the various women the aliens had abducted. Inside, Atsumi encountered Shiraishi, who had discovered the Mysterians' true intentions: to complete construction of their dome and use it to bring humanity to its knees by leveling major cities. Shiraishi allowed Atsumi and the women to escape, then stayed behind to destroy the dome from the inside. From the outside, the dome began to take damage from the assault of the Markalite Cannons. The Mysterians deployed a second Moguera, which was destroyed when it toppled a Markalite Cannon onto itself. Following repeated blasts from Markalite Cannons and the destruction of its internal systems by Shiraishi, the dome began to collapse. The surviving Mysterians boarded their UFOs and fled to their space station, as the dome finally exploded, ending their invasion.
- Exterior absorbs most attacks fired at it, including the beams from a Markalite Cannon. However, a sustained effort against the exterior will result in the base's defenses failing to function.
- The Mysterian Dome can fire a powerful ray cannon which is capable of destroying or burning most material.
- The Mysterian Dome has a hangar within it that allows the launch of Mysterian UFOs.
- The Mysterian Dome possesses a rotating disc-like base that allows the dome to burrow and produce powerful earthquakes.