The original Kamen Rider. He was altered into a cyborg by the evil Shocker organization, but retained his humanity, choosing to fight evil in the name of justice.

While practicing for the grand prix, Hongo followed a group of bikers who were calling him out, only to fall into a trap sent up by terrorist organization Shocker as they convert him into a super-powered cyborg before he woke up a week later as they are about to complete the process with brain washing. However, Hongo manages to escape Shocker's base by chance due to his college professor Midorikawa, who has been working for Shocker and was the man who selected Hongo to join the organization. The two are pursued by the Shocker Inhumanoid Spider Man and his forces as they hide out at warehouse 55 at the habor. Unfortunately, Spider Man managed to track Ruriko to their location and kills the Professor as Ruriko arrives, blaming Hongo for her father's death before Spider Man takes her. Pursuing them, Rider #1 fights through Spider Man's minions before battling the Inhumanoid, killing him with a Rider Kick.

As the Kamen Rider, Hongo battles Shocker's monsters before learning that Shocker recreated the original Kamen Rider cyborg design on Ichimonji Hayato in an effort to combat the threat that Hongo posed to their organization. Hongo helped Ichimonji escape from Shocker, leaving him to fight Shocker as Kamen Rider #2 while he left the country to fight Shocker's other branches around the world. Eventually, Hongo returns to Japan and, as Kamen Rider #1, joins forces with Ichimonji as the "Double Riders" to finish Shocker and then destroy the Gel-Shocker organization that formed soon after.

Kamen Riders #1 and #2 next appeared in the sequel Kamen Rider V3. The titular V3 was Kazami Shiro, a junior of Hongo's, and begged them to turn him into a Kamen Rider after the murder of his family by the Destron organisation. Despite initially refusing, when the young man was mortally wounded assisting them, the two Riders transformed him into Kamen Rider V3, possessing both Kamen Rider #1's "skill" and Rider #2's "strength". The Double Riders were apparently killed detonating an atomic bomb, but reappeared alive and well later on in the series.