Sougo Tokiwa who always dreamed of becoming a king encounters a mysterious girl who came from the future and warns him that he would become the king of all time, Kamen Rider Zi-O, who destined to rule the world.

The series tells the story of a young man who, according to visitors from the future, is destined to become a tyrant who will subjugate the entire world, and embarks in a journey across time to change his fate, meeting other Kamen Riders from the past in the occasion.

In the fall of 2018, a time machine appears before Sougo Tokiwa, a high schooler that has always dreamed of becoming a king. Then, Tsukuyomi appears from the time machine, telling Sougo, "I come from the year 2068, a world without hope where the Oma Zi-O, the king of time reigns supreme." She has come from the future in a desperate effort to change her own time. She then gives Sougo an ominous warning, "You will become Kamen Rider Zi-O, King of Time, the demonic king destined to rule the world." Can this really be Sougo's fate? This is the story of a Kamen Rider who would be king, who will fight to save the past, present, and future, encountering the various Heisei Kamen Riders throughout space-time.—TOEI

Sougo Tokiwa, a high school student born in the year 2000, has always dreamed of becoming a king. Suddenly, he encounters a mysterious girl named Tsukuyomi, who has come from the year 2068 with an ominous warning: "You will become the king of all time, Kamen Rider Zi-O, a demonic king destined to rule the world." Despite being troubled by his potential fate, Sougo takes up the mantle as Kamen Rider Zi-O to stop the Time Jackers from destroying the very fabric of space-time while protecting the legacy of the Heisei Kamen Riders that came before him.—Mwd