This article is about a/an web episode in Kamen Rider Zi-O.

Rules of the World (世界のルール Sekai no Rūru) is the second episode of Kamen Rider Zi-O: Supplementary Plan. It was released on TTFC accompanying second episode of Kamen Rider Zi-O as it's "episode 2.5".


What are the rules of the world where our characters living? There are answers...

Rule 1: Two Riders with the same power cannot exist at the same time (Another Build exists, so Build cannot).

Rule 2: Another Riders can only be defeated by the powers they’re based on (Zi-O has to use Build’s power to defeat Another Build).

Rule 3: People who nitpick the adult's details will be kicked by a horse.

With the event of Build had been interfered by Time Jackers, The event itself disappeared from history. Thus, making of what happened to everything on Build's story had been erased and replaced by unknown event.



Guest cast


  • Takumi Katsuragi's family name is spelled "葛木" (Katsuragi) in the script.


  • Rule 1 seems to conflict with the "Legend Rider" devices that exist in past series.
    • Said rule can be interpreted as only occurring due to the Time Jackers altering the history of Riders. It can also be suggested that some of the "Legend Rider" devices may not be completely the same from the powers they've originated in contrast to how the Another Riders fuctions.
  • As the series progressed, more indications occurred that conflicted with Rule 1:
  • Rule 1 mirrors the limitation of the Morphin GridIcon-crosswiki from the Power Rangers franchise in that it does not allow two Rangers with the same power set to co-exist for a long period of time.
  • When Sento/Takumi explains the Rule 1, the American folk song Turkey in the Straw is played in the background.
  • Sento/Takumi mentions Evolto in this episode.
  • This episode's title brings to mind one of the catchphrases of Masamune Dan: "I set the rules of the world"


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