I'm really just human

Natsukawa accidentally traveled to an alternative Ultra Universe similar to the world of "Shin Ultraman" and became Kaminaga Shinji who had just separated from the New Ultraman.
However, as a former human incarnation of Ultraman, Natsukawa was surprised to find that he had become an outcast of the times.
Five years have passed, Ultraman has been forgotten by humans, and the era of Kamen Rider has arrived. Xia Chuan, who only has the Ultraman Fighting Evolution System, has not only lost his hope of becoming a life form of light because of Zoffy, but his application for Kamen Rider qualifications has also been repeatedly blocked...
This is a story about an out-of-date hero seeking a path to super evolution in the dark universe.