The night Kamen Rider W was born is the night Shoutarou stopped being just a detective and became someone willing to carry impossible weight. This movie doesn't explain W's origin as a victory, it shows it as a scar, the moment a kid had to grow up faster than any kid should. Tokime asking the questions you've been asking since the first episode, Shoutarou finally answering them, and neither of them getting the relief they deserve, that's the gut of it.

Tokime hunts for answers about Gaia Memories, the shadowy city of Shadow Fuuto, and her own connection to it. Her questions lead to a confession from Shoutarou, who recounts the night that changed everything: the moment Kamen Rider W was born. Years earlier, a young Shoutarou works as an assistant to the private investigator Sokichi Narumi, the mentor he calls his old man, and tries to follow in his footsteps despite being dismissed as half-baked. Dopants, people wielding the power of Gaia Memories, have begun to surface in the shadows of Fuuto. Shoutarou has no idea that Sokichi is secretly fighting as Skull, and his frustration with his mentor grows. Then the agency receives a mysterious call that draws them toward a fateful night. The film reveals the origins of W, the one detective made of two, blending action, mystery and supernatural drama into a story of mentorship and the start of a legend.