

The next day, the Riders infiltrate the base, only to get caught in a trap. A vengeance-fueled Shiro asked the Riders to turn him into a cyborg. Shortly after he drove off the Destron forces, Kamen Rider 2 shows up, but too late. Hasami Jaguar then prepares to kill Junko and Shiro but is stopped by Shiro's high school teacher, Takeshi Hongo, who transformed into Kamen Rider 1. When he returned home, he found his family being murdered by the Hasami Jaguar, a jaguar monster with blades for hands.

Assisted by motorcycle race team manager Tobei Tachibana and FBI agent Kazuya Taki, the Kamen Riders fought in both solo and partnered missions against both Shocker and its successor organization Gel-Shocker. Another of Shocker's victims, freelance photographer Hayato Ichimonji, had also been given cyborg implants but was saved by Kamen Rider from the brainwashing process to become Kamen Rider #2.

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 1. However, one victim named Takeshi Hongo escaped just before the final brainwashing. To further its plans for world domination, Shocker recruited its agents through kidnapping, turning their victims into mutant cyborgs, and, ultimately, brainwashing them.
