The story took place in a world plagued by Shocker, a mysterious terrorist organization. To assist its plan in world domination, Shocker recruited its agents through kidnapping, turning them into mutant cyborgs and, ultimately, brainwashing them. However, one of the victims was rescued just before the final step, and his name was Takeshi Hongo. With his sanity and moral conscience remaining intact, Hongo assumed the identity of the grasshopper-looking altered human (改造人間, kaizō ningen?) superhero Kamen Rider and battled Shocker with his newly acquired powers.