R13 is an investigator for the Bureau of The Human Development in 28th centuries Tokyo. His job is to protect the society from all kinds of Regresivists who want to revert humanity back to 21 st century.

Together with his diligent cat-ears assistant Mizuki. He will try to protect the prosperity of the human race. With the passing time he will, however notice that the biggest danger to humanity was technology and so called Medusa Effect.