Kamen Rider Outsiders is a TTFC-exclusive series serving as a crossover between various Kamen Rider series. Immediately following the abrupt ending of Kamen Rider Genms -Smart Brain and the 1000% Crisis-, multiple Kamen Riders fight against the villainous schemes of a returning Foundation X and Zein.

With the collapse of ZAIA Enterprise Japan, Gai Amatsu establishes a new company with a presidential aide model Humagear, Rin. Suddenly, something happens to his body, and Kuroto Dan emerges! The Bugster Virus, which was wandering the internet, was revived by Ark and infected Gai!