In the near future, the evil alien Radam has besieged the Earth, gaining control of the enormous Orbital Ring that surrounds the planet and rains down mysterious spores that infest the Earth with dangerous alien plants. Aki and Noal, two pilots from the Outer Space Development Group, find one of the alien lieutenants who crash-landed on Earth. The stranger claims to have no memory, and is determined to fight to protect humanity! His name is D-Boy, and he appears to be a normal human until he transforms into the bio-mechanical warrior, Tekkaman Blade!