The series takes place in a world plagued by Shocker, a mysterious terrorist organization. To further its plans for world domination, Shocker recruited its agents through kidnapping, turning their victims into mutant cyborgs and, ultimately, brainwashing them. However, one victim named Takeshi Hongo escaped just before the final brainwashing. With his sanity and moral conscience intact, Hongo battled Shocker's minions as the grasshopper-themed altered human (改造人間 kaizō ningen?) superhero Kamen Rider. Another victim of the altered human process, freelance photographer Hayato Ichimonji, became Kamen Rider 2 after Kamen Rider, who renamed himself as "Kamen Rider 1", saved him from Shocker's brainwashing. Assisted by motorcycle race team manager Tobei Tachibana and FBI agent Kazuya Taki, the Kamen Riders fought in both solo and partnered missions against Shocker and its successor organization, Gel-Shocker.