Joji Yuki (結城 丈二, Yūki Jōji) is a former member of the organization known as Destron who becomes Riderman (ライダーマン, Raidāman) to seek vengeance against Marshall Armor. He is also known as The Avenging Demon (復讐の鬼, Fukushū no Oni) or Kamen Rider 4 (仮面ライダー4号, Kamen Raidā Yon-Gō).