The invaders from Planet X attack earth as part of their plan to conquer the entire universe, using a legion of space monsters. The earth sends Godzilla, the strongest monster on the earth, and Mothra, to defend itself. Godzilla advances through 8 battle stages to defeat a legion of space monsters controlled by Planet X. For the sake of the future of the earth, Godzilla's fierce battle now begin...

The mysterious Planet X appears when Pluto and Neptune switch positions in the solar system, and its inhabitants begin an attempt to conquer the Earth, using a legion of space monsters (though some of these creatures were in fact from Earth) as their primary attack force. The King of Monsters, Godzilla, joins forces with the guardian monster Mothra and the forces of Earth to repel the invasion forces.