Hoshi was an aspiring writer who was well-known for a fanfic revolving around his OC Kamen Rider. One night, he comes across the character he created, who passes to him his Rider Belt before succumbing to his wounds. Now caught in a war between what were once fictional characters, Hoshi must become Kamen Rider Dante and tame his fiery emotions before those flames consume him.

Set in the aftermath of Ex-Aid Episode 27, pediatrician and former gamer prodigy Emu Hojo encountered a new crisis in the form of a pop culture figure coming to real life and threatening it. Joined with the benevolent figures of the same background, Emu must solve the crises that transpire altogether. But with a seemingly uneasy alliance, can he prevail as Kamen Rider Ex-Aid?

If there's one thing I can saw now…is that I'm sure that a miracle was born and with it…a story that surpassed all stories was created. My name…just call me Retsu Mikado…and this is my story: the story about a boy and a girl, and their actions that caused a whole universe of characters to collide. (OC SI Rider inbound. Proceed with caution)