After a crushing defeat by a new adversary, the Crisis Empire, Kôtarô Minami receives a miraculous and powerful new upgrade for his Kamen Rider Black persona, Kamen Rider Black RX, and thus battles the forces of Crisis.

After the defeat of Gorgom, Kotaro Minami begins a new life for himself, only to be abducted by the Crisis Empire. Their General Jak offers him to join with them and destroy earth. Kotaro refuses and his Kingstone is destroyed. He escapes from the crisis and falls through, until the Kingstone absorbs the power of the sun. Kotaro is reborn as the child of the sun, Kamen Rider Black RX and his old bike Battle Hopper is also reborn as Acrobatter.