Kouhei and the five Micromen were enjoying a brief period of peace. However, the passenger plane carrying Kouhei's family mysteriously vanished. At the same time, strange phenomena involving the disappearance of buildings and other structures began occurring frequently around the world. Believing it to be the work of the evil Acroyear army, Arthur and the other Micromen, detecting gravitational anomalies, hurriedly take Kouhei to a mysterious island floating in the Pacific Ocean. There, waiting for them, was Golgon, the strongest warrior of the Acroyear army, who plots to conquer Earth and erase all of humanity! This is the theatrical animation of "Little Giant Microman," released as part of the 1999 Toei Anime Fair in the summer.