The appearance of the giant living creatures “Kaiju's” and the ultimate existence that destroys all monsters, Godzilla, has incited a battle that lasted for half a century. Humanity has experienced continuous defeat, and finally plans to escape from the Earth. In 2048, only those who were selected by the A.I. managed under the central government boarded the inter-sidereal emigrant spaceship “Aratrum” to head for “Tau Cetus e”, the planet beyond the distance of 11.9 light-year. However, the environmental condition differences between that of the Earth and Tau e were considered to be inhabitable by human beings. The young man on the emigrant ship: Haruo, who saw his parents killed by Godzilla in front of his eyes, had only one thing in his mind for 20 years: to return to the Earth and defeat Godzilla. Shut out from the possibility of emigration, as the living environment in the ship deteriorates, the group of “Earth Returnists” led by Haruo are determined to return through a dangerous long-distance hyperspace navigation. However, 20,000 years have passed on Earth since and it has become an unknown world with the ecosystem reigned by Godzilla.