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.

Long ago, a great, destructive war between humans the Orgs was ended; the people of Earth were believed to be the victors. But now, 1,000 years later, the Orgs have returned. And five new warriors have been selected by the Power Animals to claim the responsibility of protecting humanity once again, by becoming Gaorangers!

It is the year 1999. The Machine Empire of Baranoia, led by Emperor Bacchus Wrath, has invaded Earth with the intention of wiping out all human life and bringing about machine rule. Chief Counselor Miura of the UAOH (United Airforce Overtech Hardware), in a desperate attempt to quell this invasion, has revived super energies born of the lost civilization of Pangaea. Enlisting an elite squad of the finest officers the UAOH has to offer, Miura has harnessed Tetrahedron Power, granting the team the power to transform into the Ohrangers… and save humanity from its darkest crisis yet!

Kintaro Yajima comes to Tokyo and is hired by Yamato Construction Company when he saves the life of the company's CEO. A former leader of a motorcycle gang, Kintaro is known for his highly principled and forthright way of dealing with matters and is never afraid to tell his superiors exactly what he thinks. This has a tendency of irritating some; but when corruption from within the company begins to surface, he may be the only one who can stand up to it.