This paper toy is the Kamen Rider Double (Kamen Rider W), designed by Azrael. Kamen Rider Double (aka Kamen Rider W) is the main and eponymous protagonist of the Kamen Rider Series Kamen Rider Double. Double is the first Kamen Rider that transforms from two people. His debut appearance was a cameo in the film Kamen Rider Decade: All Riders vs. Dai-Shocker. According to the producers, he was originally going to wear a trenchcoat in his henshin form, but it was decided not to include it.
The right half Double, providing the 'mind,' he disappeared after being broken down into data but came back a year later, thanks to his mother and sister. The left half of Double providing the 'body' and a self-dubbed Hardboiled Detective. Shotaro is also a Kamen Rider on his own as Kamen Rider Joker.
When Shotaro and Philip set their Gaia Memories into the Double Driver Belt, Philip's conscious mind enters Shotaro's body to produce Double. Their quote at the start of a battle is "Now, count up your crimes!", a quote originally used by Sokichi Narumi.
When combined as Double, Shotaro usually does most of the talking, though both speak when saying their pre-battle quote and announcing Maximum Drive attack names. When Philip speaks by himself when transformed, Double's right eye flashes. Double's ability to function is dependent on the condition of both Shotaro and Philip. If their synchronization is somehow disrupted, Kamen Rider Double will be unable to move properly. If their Rider form takes any damage at all, both of them will feel the pain after returning to normal and Philip will often pass out due to his weaker constitution. Shotaro's habit of flicking his wrist carries over to Double.
Kamen Rider Double is unique among Kamen Riders in that rather than having explicitly defined forms, he instead has mix-and-match powers. Through the different Gaia Memories, Double has access to various combinations of powers, weapons, strengths, and weaknesses. Kamen Rider Double's forms accessed through their first six Gaia Memories are known as Half Changes, due to the fact that Double can switch out one Gaia Memories in the belt in a Memory Change to change forms.
Each different version of Kamen Rider Double has its own finishing attack known as Maximum Drives, which is needed to defeat a Dopant. The energy imparted by the Maximum Drive does not destroy the Dopant but rather its Gaia Memory, resulting in the ejection of the Gaia Memory from the user's body and the destruction of the Gaia Memory, hence why such a procedure is called a "Memory Break".