Taking place after Kamen Rider W Returns: Kamen Rider Accel, Fuuto PI revolves around Shotaro Hidari, a private detective who works at Narumi Detective Agency, and his partner Raito “Phillip“ Sonozaki, the sole survivor of the Sonozaki family who can access the Gaia Library. Together they transform into Kamen Rider W, who protects the city of Fuuto from Dopants, monsters created by Gaia Memories. They solve cases alongside their boss Akiko Terui, who often joins their investigations with her husband Ryu (a member of the police force who is also Kamen Rider Accel). One day, Shotaro encounters a amnesiac pink-haired girl named Tokime, who is being targeted by Dopants. After saving her, they decided to hire her at Narumi Detective Agency as their assistant. As Shotaro and Raito solve more cases, they gradually uncover Tokime's connection towards the mysterious Dopant Aurora.