"FUUTO PI" is a detective anime series set in the fictional city of Fuuto, where crime and mystery intertwine with the use of advanced technology. The story centers on Shotaro Hidari, a hard-boiled private investigator with a strong sense of justice, and his partner, Philip, a brilliant but enigmatic young man with vast knowledge and analytical skills. Together, they operate the Narumi Detective Agency, taking on cases that often involve the mysterious Gaia Memories—USB-like devices that grant users superhuman abilities but come with dangerous side effects.

The narrative begins with the duo investigating a series of crimes linked to the misuse of Gaia Memories, which are distributed by the sinister organization known as the Museum. As the cases unfold, Shotaro and Philip uncover a deeper conspiracy involving the city's elite and the true purpose behind the Gaia Memories. The detectives use their own Gaia Memories to transform into the vigilante Kamen Rider Double, combining their strengths to combat the Dopants—criminals who have been corrupted by the power of the Memories.

Throughout the series, the partnership between Shotaro and Philip evolves, with Shotaro's street-smart intuition and Philip's intellectual prowess complementing each other. Their investigations lead them to confront various antagonists, each with their own motivations and connections to the Gaia Memories. The story also delves into the personal histories of the main characters, revealing Philip's mysterious origins and Shotaro's unwavering commitment to protecting Fuuto.

The plot is driven by a mix of episodic cases and an overarching narrative, blending action, mystery, and character development. The series explores themes of justice, identity, and the consequences of wielding power, all set against the backdrop of a city grappling with the dualities of progress and corruption. "FUUTO PI" maintains a balance between standalone detective stories and a larger, interconnected plot, making it accessible to both new viewers and fans of the Kamen Rider franchise.