A giant monster appears from the ground, after the eruption of Mt. Myojin. In the meantime, Japanese government asks help from the scientist Dr. Saigo and his daughter Miwa. Both work at the Institute of Super Physics and Chemistry and were once ousted from the academic world on suspicion of forging materials concerning what the two scientist announce to be a universal cell, "Setap X". Using the Setap X, Dr. Saigo transforms his assistant, Hideto Nitta, into a giant wrestler with a height of 40 meters. The latter challenges the monster from Mt Myojin, named Mono by members of a Kaiju organisation.
