Joji Yuki, known as Riderman, is a key character in the original Kamen Rider series, 'Kamen Rider V3.' Once a scientist working for the evil organization Destron, he is betrayed and left for dead, losing his right arm. He survives and seeks revenge, becoming Riderman to fight alongside Kamen Rider V3. Riderman’s journey from villain to hero makes him a complex and sympathetic figure, ultimately sacrificing himself for justice and his allies.