Based on

Movies like Kamen Rider Den-O The Movie: I'm Born! (2007)

With Gaoh having stolen the DenLiner and trapping the Imagins onboard, Ryotaro and Hana find themselves trapped in the year 2000 where they meet Ryotaro’s younger self, but Ryotaro is slowly forgetting everything having to do with Den-O! As Gaoh gets closer to his target, the only hope lies with Yuuto’s complex plans and a little bit of luck, or else time itself could fall victim to Gaoh’s evil desires!