The Dogma Kingdom attacks the Matagi (mountain tribe) village of Yamabiko to steal the sacred Flying Dragon Fortress and wreak havoc all over Japan. Six children from the fallen village take refuge in a nearby town, keeping their identities as Matagi citizens a secret. Kamen Rider Super-1 must protect these children from the Dogma Kingdom, as they hold the secret to the Flying Dragon Fortress' weakness.

Professor Daidōji has developed a gravity machine called the GX Device. Unfortunately, Shocker wants it; so they attack the professor and destroy his laboratory, but come home empty-handed. Shocker's agents find out that the plans for the GX Device are with Daidōji's daughter, who is celebrating her birthday. Now the Kamen Riders, along with FBI agent Kazuya Taki, must protect Daidōji's daughter and prevent Shocker from obtaining the plans.

A physicist named Tetsuo Okita discovers a new mineral called "Satanium," which is more powerful than uranium and emits destructive effects to anyone exposed to it. However, Destron abducts Okita in hopes of finding the source of Satanium and collecting more of it to expedite their run for global domination. Kamen Rider V3 must act fast in rescuing Professor Okita and preventing Destron from collecting more of the deadly mineral.