It is the near future, in the 100th year of Showa (year 2025). The population of world is more than 10 billion, and a world-class space development project called "Mars Terraforming Project" is in process.

One day, a spaceship "Izanami" crashes in Japan on the way from Mars, and it revives the monster Negadon, which was captured by the spaceship. Can the human race knock down the monster?

Under the desperate situation, a middle aged man Ryuichi Narasaki rises up against the monster. He is an expert of robot engineering who lost his daughter in an accident which happened during his experiments. Now, a desperate struggle of Narasaki and Negadon begins!