Shoutarou Hidari, a tough private detective from the Narumi Detective Agency, works to keep peace in Fuuto alongside his curious partner Philip. One evening, Shoutarou encounters a mysterious woman named Tokime who becomes linked to multiple homicide and theft cases. His investigation points to individuals using Gaia Memories—data chips resembling thumb drives—to transform into powerful Dopant creatures. Although most Gaia users were eliminated by the detective squad in earlier battles, some still persist and threaten public safety. Now Shoutarou and Philip, righteous Gaia users, must fight as Kamen Rider W to eradicate the dangerous Dopant menace. All the while they uncover Tokime's true identity and confront a forgotten, long-hidden past. Their relentless pursuit reveals that Tokime was once a former Gaia operative, betrayed by her own organization, and now seeks redemption by dismantling the rogue Dopants that threaten Fuuto's fragile equilibrium for safety.
