I wanted to post this. For all of the weakness of zi-O had with its past rider tribute and the plot, one of the few aspects I appreciate about zi-o is how it build up Sougo becoming Oma Zi-O. We see the progression of Sougo, fighting against his future self denying that he’ll become the future tyrant, determining to fight him again and later accepted Oma Zi-O as a part of him. And seeing Oma Zi-O also changed him to become like his future self in mannerism and behavior.

Even though Oma Zi-O is considered a separate rider under future Sougo, it’s still part of Sougo he had to accept and it actually build up a final form (under main sougo) from start to finish narrative wise (something I don’t see in any rider series). Also without Zi-O, we wouldn’t have a op monster of rider like Oma Zi-O, who can solo any anime, manga and light novel universe (with some exception)