1954, Godzilla first raided Japan. Tokyo was totally burnt in a night but finally the monster was killed by a newly-developed weapon. Since then, huge monsters continue to attack Japan for half a century and the weapon begins to lose its deadly effect. In 2003, armed with the most powerful weapon in the world history for the fight, a new invincible robot Mechagodzilla is about to be completed. During a test, an unexpected huge shadow rises from the deeep ocean... The battle of the century is under ignition!