Concealed in the depths of the great lands of Seatopia, a living god sleeps. Laying in slumber within his sculpted frame, an untapped power that is unequalled coleuses. Revered as the symbol of Seatopia's Kingdom, the giant was worshipped daily. But the prayers in his name were never as strong as when the people of the undersea city challenged war against the surface dwellers. Calling and pleading with the creature, they shouted for revenge on the lands of Japan. For their ignorance, the human race will die, and their blood would run in great torrents in flashing rivers. Screaming for their savior, the god awoke and shrieked into the sacred lands. Then, in a blinding act of speed, took to the air, and began it's ascension to the surface. It did not take the insect beetle long to tunnel through the layers of rocky strata, and soon it made its presence felt. Attacking with unrelenting fury, tanks, jets, and men met their fates. All being crushed at the burning standards of the rampaging creature.
The road of mankind's survival looked grim, until the intervention of a robot. Originally captured and controlled to lure Megalon to its targets, Jet Jaguar gained freedom. Striping the bonds of its Seatopian controllers, through the help of its creator, the robot grew to a massive size and prepared to battle. Assaulting the armored creature with a fury of punches and kicks, it seemed that the light at the end of the tunnel would be realized. But more tricks were yet to be revealed. Seeing that trouble could arise from their strayed robot, the king of Seatopia quickly sent word to the colony of Nebula Space Hunter M for Gigan. Adding in their struggle, the cyborg arrived on Earth and changed the tide of battle. Double-teaming the hapless Jet Jaguar, the demonic duo was about to literally shred that humanoid machine to pieces, when Godzilla arrived on the scene. Beckoned by the man made machine earlier, the leviathan turned the battle once again and for the final time. Alarmed and fearful, Gigan retreated to space, leaving its ally at the mercy of the terrestrial heroes. Bashing the god a bit more, Megalon finally was given a breather in which it took the opportunity to flee. Diving back beneath the ground, heading back to Seatopia. Where, it has since stayed at bay.