Joji Yuki is a former member of the organization known as Destron who becomes Riderman to seek vengeance against Marshall Armor. He is also known as The Avenging Demon or Kamen Rider 4.

Unlike his predecessors, Riderman is not an altered human, excluding his mechanical right arm. Instead, he gains power from the Riderman suit, being physically enhanced upon wearing it. This has allowed Joji Yuki to perform several superhuman acts such as: hold his own against Stronger in human form, defeat an army of super-soldiers, and survive an explosion powerful enough to blast him into outerspace.

Following the surgery by fellow Destron Scientists which replaced his arm, Joji Yuki can transform into Riderman. While a belt is part of his Riderman Suit, it is not the source of his transformation. Instead, Joji Yuki transforms by raising his hands in the air, with his helmet materializing in his hands. He then puts on the helmet, followed with the rest of the suit materializing onto Joji Yuki.