[Aoi Kurenai]

So I just realized people thinking Zi-O is a female comes from this:

https://i.imgur.com/oJJ2vaa.png

Which people are giving credence to because the person called Zi-O having "Rider" spelled out on their face. The way it's worded sounds more like one of the original ideas for the show was to have a female but that clearly changed. The same poster earlier said another idea involved Rider personalities being switched into different bodies. (so you'd have Takumi acting like Takeru or whatever)