In 2199, Earth has been turned into a barren wasteland due to continuous attacks from aliens on Gamilus. The remaining humans live underground. However, friendly aliens from Iscandar contact them and provide blueprints for building a powerful space battleship that can retrieve a device to clean the planet before humanity vanishes. The United Nations Cosmo Navy, whose fleets have been destroyed by Gamilas forces, revives the sunken Yamato battleship and incorporates alien technology into it, transforming it into the Space Battleship Yamato.