Let's talk about Kamen Rider W for a sec here... according to the wiki, Fuuto PI is set 2 years after the show's finale.
So the events of Fuuto PI happened when Gentaro was concluding his fight against the Zodiarts and at the same time, Haruto was already protecting
Koyomi.
I'm posting this to have better sense of the Rider Timeline... as its so apparent that W, OOO. Fourze, and Wizard all share the same universe.