Oma's Day

The day of Ohma is an anticipated event in near future in Kamen Rider Zi-O. What exactly will happen on this day is different from timeline to timeline.

Ohma Zi-O's timeline
On this day, Zi-O will transform to Ohma Zi-O and control seven giant monstrous machines called Dai Mazines to destroy the world along with all Kamen Riders and become the "Demon King." This global catastrophe will create the dystopian timeline where Geiz Myoukouin, Tsukuyomi and the original Woz came from.

Geiz Revive's timeline
On this day, Geiz Revive will defeat Oma Zi-O and save the world, becoming its savior and creating a new history. Sometime after this day, Another Woz will travel to the current day to assist Geiz.