While testing the Birth X Driver, Shintaro Gotou is shunted into a parallel world filled with many familiar faces in unfamiliar places. Can he master the secrets of the Birth X Driver and return home?
As the ancient king OOO continues his onslaught on humanity, Kougami gathers his former employees to create a resistance... and introduce a new weapon in the fight!
The year is 2021 and the world is in a state of chaos and fear. The ancient king OOO has come back to life after 800 years of dormancy. As the Kougami Foundation mounts a human resistance, Eiji Hino returns to Japan, believing he has at last found the means to revive the Greeed Ankh...
A young daughter (Mana Ashida) supports her father (Etsushi Toyokawa) who is diagnosed with Alzheimer's disease.
Eiji Hino is a wanderer who has no place to call home and a tragic past. When metallic creatures known as the Greeed awaken after their 800-year slumber to attack humans and feed off of their desires, the disembodied arm of the Greeed named Ankh gives Eiji a belt and three Medals to fight the other Greeed as Kamen Rider OOO. The mysterious Kougami Foundation approaches Eiji and begins assisting him in his fight against the Greeed, though their true motives are not clear. As Eiji fights the Greeed and their Yummy monsters, learning more about the Greeed and Ankh, he starts to find a purpose beyond his journey.