Kamen Rider 4 (仮面ライダー4号 Kamen Raidā Yongō) is a cyborg created by Shocker. He is the fourth Kamen Rider following Kamen Rider 3 and the original Double Riders, Kamen Rider 1 and Kamen Rider 2. Created to accompany the appearance of Rider 3, who originated in the manga Kamen Rider 3 vs. General Black, in the movie Super Hero Taisen GP: Kamen Rider 3, Rider 4 appeared in a DVD special accompanying the film's release.
Kamen Rider 4 was shown being built after credits when Shocker revealed that the failure of Kamen Rider 3's attack was not the end of their plans to use the History Modifying Machine and conquer Earth.
Kamen Rider 4 was born as a plan when Shocker scientists recovered the functioning remains of the History Modifying Machine and began messing with the machine. As they did, they trapped the present in a temporary timeloop in an alternative timeline, one where Mach was alive even after the events of Shocker's previous attempt with the machine. As Kamen Rider Drive sacrificed his life to save Mach in the third time loop, and another time loop started, Kamen Rider 4 was near completion, his Sky Cyclone waiting for him in another hangar.
During the climax of their fight, Kamen Rider 4 clashed his Rider Kick against Kamen Rider Drive Type Formula's Formula Drop, which he had initially blocked with his own Rider Kick, but Drive broke the clash by twisting his kick as so he went airborne while 4 hit the ground, his leg damaged when he stood back up. When Drive came back down to resume his Formula Drop, 4's leg was too damaged to attempt another Rider Kick clash, and resorted to clashing it with a Rider Punch. Despite the power, the Rider Punch was snuffed out, and Drive was pushing 4 back. Drive resorts to throttling Shift Formula 5 times, then an additional 3 times after ignoring some warnings from Krim, finally overwhelming 4 and destroyed him.
Soon after this, Kamen Rider 4 was somehow rebuilt by Shocker, before disappearing from their base.
In his initial appearance, he seemed to be based off of Kamen Rider 3's prideful behavior to a greater extent,becoming more sadistic than his predecessor,taunting Drive by saying that he would destroy all of the Riders, again and again, until Shocker ruled the world, taking delight in beating Shinnosuke.
- Rider Height: 205 cm
- Rider Weight: 105kg
- Ability Perimeters:
- Punching Power: 20 tons
- Kicking Power: 28 tons
- Maximum Running Speed: Unknown
- Maximum Jump Height: 100m
Like his predecessor, Kamen Rider 3, Kamen Rider 4's body is that of a cyborg; however, unlike his predecessor, or successors, his is much more mechanical than human, with his head, arms, legs, and pats of his chest being entirely mechanical. This gives him a greater aversion to pain over any other Riders, and gets rid of his exhaustion, which allows him to fight longer than most Riders could, tiring his opponent before destroying them entirely.
- Kamen Rider 4 is the second Kamen Rider who can be considered a Showa, Heisei, and Neo-Heisei Rider, with the first one being his predecessor Kamen Rider 3.
- Kamen Rider 4 was portrayed by Mitsuru Matsuoka, who previously played Kamen Rider Eternal in Kamen Rider W.