In the United Global Year (UGY) 193, the Earth is under attack from an extraterrestrial enemy: the Radam. Leading them are an even deadlier force, known as the Tekkamen.
Surrounding the Earth is the huge man-made orbital ring known as the Space Ring. Constructed well before the arrival of Radam, it was the first human structure attacked. As the aliens attacked, it was largely abandoned, left to serve as a battle ground for Blade and the Tekkamen.
Fighting against the invaders are the Space Knights led by Commander Heinrich Freeman. They consist of Noal, the pilot of the spaceship Blue Earth; Aki Kisaragi, the Navigator; Milly, Communications Operator; Rebin, computer wiz and mechanic; and Honda, Mechanic and Repairs. The Space Knights have been unsuccessful at repelling the Radam until the arrival of D-Boy, a mysterious young man who has the ability to transform into the powerful warrior known as Tekkaman Blade.