As shown in episode 27, Ryotaro pursues the Molech Imagin to May 8, 2000. Though Den-O Sword Form destroys the Molech Imagin, the Imagin fulfilled his mission as the Den-Liner ends up hijacked by the rest of the Imagin led by a rogue Kamen Rider named Gaoh. After stealing Owner's Master Pass and trapping Urataros and Kintaros, Gaoh forces the Den-Liner to travel back in time via "God's Line" to the Edo Period of Japan so he can retrieve the legendary God's Train, the Gaoh-Liner. Trapped in 2000, Ryotaro and Hana encounter Ryotaro's younger self at age 11 as well as their old friend, the Imagin Sieg. In order to prevent confusion between the two incarnations of Ryotaro, they call the younger one "Kotaro". By the time Yuto finds them, Ryotaro has lost his memory of everything related to Den-O and as a result, Momotaros cannot possess him, forced to take Kotaro as a host instead. However, Sieg's special talents allow him to still possess Ryotaro, offering his aid when the gang uses Zero-Liner to pursue Gaoh, with Kotaro joining them. After being sent into the Mesozoic period by Gaoh, the gang arrived in the Edo Era and get Senhime's aid in sneaking into the camp of Yukimura Sanada, who is aiding Gaoh. Though the reunited Tarōs defeat Sanada's ninjas, Gaoh succeeds in obtaining the Gaoh-Liner and travels forward to December 26, 1988, the day Ryotaro was born, to make an example out of Ryotaro. Ryotaro and Momotaros are forced to fight him and band on his own until Yuto arrives with the past Ryotaros he borrowed for the "Climax Scene". After the long battle, the Den-Os and Zeronos emerge victorious as Gaoh is destroyed by Sword Form. On the return trip back to his own time, the Den-Liner comes across Ryotaro's old house as Ryotaro finally gets to see the face of his parents for the first and last time. Sieg and Kotaro also return to their respective timelines as well, resuming their places in history. When Ryotaro returns to the present, he finds a drawing of his parents in the picture frame where the original photo once was
