The city of Yūbari in the Hokkaido prefecture has become a ghost town following the presence of Shadow Moon and his minions of Gorgom. Makino, a scientist working on Gorgom's top-secret robot experiment, escapes from the evil organization and returns to Tokyo, only to find out that his wife and daughter have been abducted. As Kamen Rider Black, Kotaro travels to Yubari to save Makino's family and liberate the town from Shadow Moon's evil grasp.
Originally known simply as Kamen Rider Black during its theatrical release. Children all over Tokyo mysteriously disappear without warning. Kotaro suspects that the Gorgom are behind the abductions and follows a suspicious-looking tour bus with children on it, only to lose its trail off a cliff. With the help of a fisherman, Kotaro travels to a remote island and uses his abilities as Kamen Rider Black to save the children and foil Gorgom's latest evil scheme.
In the film, the Crisis Empire devise a plan to defeat Kohtaro Minami by reverting him back to his old form of Kamen Rider Black and sending out several revived monsters after him. However, Kamen Rider Black is assisted by another RX, who used a time warp to help his past self. The two are joined by RX's alternate forms of Robo Rider and Bio Rider and the four Kamen Riders combine their powers to defeat the revived monsters.