Sougo Tokiwa, a high school student born in 2000, dreams of one day becoming a king. He finds himself recruited by a mysterious girl named Tsukuyomi, who came from a dystopic future in the year 2068 and gives him an ominous warning: "You will become Kamen Rider Zi-O, the King of Time; the demon destined to rule the world." While troubled by his possibly cursed fate, Sougo becomes Zi-O so he can save the time and space continuum while encountering his various Heisei Kamen Rider predecessors. However, also from the same future as Tsukuyomi, appear enemies such as Geiz Myōkōin, a resistance fighter from 2068 who transforms into Kamen Rider Geiz and intends to kill Zi-O to change the future, and the Time Jackers, a group seeking to change history by creating Kamen Rider-based monsters known as the Another Riders.