A mysterious woman claiming to be a witch steals a valuable bag from a man and claims that he can't satisfy her before vanishing into thin air. Having run across her himself, Shotaro and his trusted partner Philip take the case but quickly find that things aren't right in Fuuto, starting a new battle for the two-in-one detective Kamen Rider Double.

Note: The series is a direct sequel of the tokusatsu series Kamen Rider W and its subsequent specials.