[Librarian]

This seems rather fitting since it's the series that broke the trend of threes, and started the path for all riders to follow.

Plus, I rather like the embedded aspects of it in connotation of Zi-O.

Riders who are fighting to get a wish granted compared to Riders fighting over the once and future king alongside impostors. There's a nice theme play contrast in many regards, and makes me excited for some future potential spin-offs too in how that might further play out in other contrasts of celebratory natures from the eras.