Shigeru Jō joins the evil organization Black Satan after the death of his close friend Gorō Numata, who he considered his mentor. He, promised power, and fueled by a desire for revenge, undergoes surgery to become one of Black Satan's super warriors. However, Shigeru knows that Black Satan were in fact the murderers of his friend; he was using Black Satan in order to gain new powers. The newly powered up Shigeru escapes from the Black Satan headquarters before they can brainwash him into following their campaign of evil and becomes Kamen Rider Stronger.