Takeshi Hongo is a promising young man with a passion for motorcycle racing. However, his dreams are suddenly ruined when he gets kidnapped by Shocker, the evil secret organization planning to dominate the world. After being remodeled into a cyborg, Takeshi escapes and swears to protect the world from the inhuman monsters.

After already conquering hundreds of planets, the Great Star League Gozma sets its sights onto Earth. To defend the lands in such a great crisis, the military begins a special branch known as the Earth Defense Force, comprised of elite members from all areas of the military. Under the supervision of Commander Ibuki, the numerous gathered soldiers of the Earth Defense Force begin a harsh training.

After a Space Beast throws them off Shuttle Base, the Changeman scramble to get their ship back as Sayaka tries to protect it from the inside.

The Changeman must work with an earthquake institute to prevent Earth from being destroyed in a sea of fire by the Gozma.