The Shocker Organisation decided to create a more powerful cyborg mutant to get rid of Kamen Rider 1 and thus created Kamen Rider 2. However, before they can brainwash Kamen Rider 2, he was rescued by Kamen Rider 1 and together they set out to destroy the Shocker Organisation. Kamen Rider 1 leaves Japan to fight overseas and lets Kamen Rider 2 handle Shocker in Japan.
The truth of the matter was, the actor who was playing Kamen Rider 1 was injured doing his own stunt and had to be replaced by a new actor to keep the series going. Kamen Rider 2 was the first Rider to do the "henshin" movement i.e. transform by waving his arms. This became quite popular and all the Riders had to wave their arms to transform after that.
Originally, Kamen Rider 1's costume had teal chest plates with a white belt and dark teal helmet with pink "eyes" and teal mouthpiece. Later, the suit's color was changed to a dull green and the helmet color was deeply darkened with red "eyes". Kamen Rider 2 had the same color green as Kamen Rider 1, although the helmet had a silver stripe down the center, a silver mouthpiece, single-line stripes down the sides of his body, and a red belt. After Kamen Rider 1 returned as the star of the show (when the actor recovered from his injuries), his outfit was changed to a brighter green with a red belt, double stripes on the sides of his body, silver boots and gloves, and a helmet colored like Kamen Rider 2's. When Kamen Rider 2 returned, his costume was the same as Kamen Rider 1's, except with red gloves and boots instead of silver and single-stripes on the side of his body.
The deluxe version 2.0 box
Kamen Rider 2
Kamen Rider 2's Typhoon Belt that lets him transform.
Check out Kamen Riders group shot.