[Clockworx]

well since they is a lack of a katakana or hiragana for ZI, since its Sa/Za, Shi/Ji, Su/Zu, Se/Ze, So/Zo often times Ji doubles for Zi as well making things complicated since JI also doubles for DI like in Radio, Rajio if i'm not mistaken.

The O part is indeed clearly Ou like like king though written in kana instead of Kanji it only gives us the sound.

So we have Kamen Rider Geo/Jio/Zeo Since they did write it with Z guess its going the Zeo route so let the meme's roll in I guess.

I wonder what the theme will be.

Also in yugioh there was "Elemental Hero Ji Asu" for The Earth/Terra Firma. so Perhaps its THE King.