In the windy city of Fuuto, detective Shotaro Hidari and his partner, the mysterious Philip combine to become the two-in-one Kamen Rider, W in order to fight creatures called "Dopants" that abuse the power of items called Gaia Memories.

Renn Kiriyamaas Shotaro Hidari / Kamen Rider Double / Kamen Rider Joker
Masaki Sudaas Philip / Kamen Rider Double
Hikaru Yamamotoas 鸣海亚树子
Koji Kikkawaas 鸣海庄吉
Minehiro Kinomotoas Ryu Terui / Kamen Rider Accel
Takeshi Nadagias 刃野干夫
Rin Asukaas 园咲若菜
Minori Teradaas Ryubee Sonozaki / Terror Dopant
Hiroshi Watarias Teacher