Negadon: The Monster from Mars

The anime Negadon: The Monster from Mars takes place in a future where Earth's population has grown too large, prompting a search for a new home on Mars. To make the Martian environment habitable, terraforming was attempted, but a Japanese spacecraft returning from the planet suffered a crash landing in Tokyo. This accident released Negadon, a massive monster, onto the city streets. Dr. Narasaki and his robot, Miroku, are the only ones who can potentially stop Negadon.