This is Kamen Rider W stripped down to pure noir detective work, where the mystery matters more than the suit. The animation is so sharp it makes you forget you're watching an adaptation of a 2008 tokusatsu series, and the saxophone doesn't just score scenes, it IS the show's backbone, bleeding into every frame. You need to have seen the original series first, which means this isn't gateway content, but what you get is a 12-episode noir film masquerading as a Kamen Rider story, where the detective work between transformations hits as hard as the fights themselves.
Fuuto's streets hide a dangerous secret: Gaia Memories, small devices that transform ordinary people into powerful monsters called Dopants. The police are helpless against them. When his mentor dies under mysterious circumstances, hard-boiled detective Shoutaro Hidari teams up with Philip, a strange man with his own agenda, to take on cases no one else can solve. The two discover they can use their own Gaia Memories to become something greater: Kamen Rider Double, a combined warrior capable of fighting the Dopant threat. But these devices come with a price. Every transformation risks poisoning the user, driving them toward madness and death. As Shoutaro and Philip investigate deeper into Fuuto's criminal underworld, they uncover a conspiracy that reaches far beyond simple crime. The partnership between detective and stranger becomes the city's only hope against forces that grow more dangerous with each passing day. Loyalty, sacrifice, and the cost of power collide in this noir-tinged battle for a city's soul.