Back to 2068 (バック・トゥ・2068 Bakku tu Nisen-rokujūhachi) is the fifteenth episode of Kamen Rider Zi-O. It features the first appearance of Ohma Zi-O since episode 1.
This episode is accompanied by the fifteenth episode of Kamen Rider Zi-O: Supplementary Plan web series, Supplementary Plan Forever (Part I).
Why does Sougo want to become a king in the first place? Sougo starts to tell Tsukuyomi about the continuous dreams he's been having. Just then, a giant event, just like the one in Sougo's dream, suddenly starts to manifest! A giant mecha suddenly appears in the sky! The demonic king's servant from the future, Kasshin suddenly appears! And thanks to Decade's intervention during their fight, Sougo gets blown 50 years into the future...!