I didn't really watch the shows. Some time ago I saw a picture with these guys promoting the show. I never saw it. Years later, I walk into a hobby shop and on a shelf I see a model kit for Kamen Rider W (second guy on left) and thought "This guy seems familiar somehow." Days later at the Steam Workshop, I found the ragdoll pack for the Kaman Riders and I go "Ooooooh, so that's where he's from" Thats how I came to find out about them.
From left to right: Kamen Rider Wizard (Haruto Souma), Kamen Rider W (Shotaro Hidari & Phillip), Kamen Rider OOO (Eiji Hino), Kamen Rider Fourze (Gentaro Kisaragi), and Kamen Rider Decade (Tsukasa Kadoya).