The Japanese fishing vessel ''Yahata-Maru'' is caught in strong currents off the shores of Daikoku Island. As the boat drifts into shore, the island begins to erupt, and a giant monster lifts itself out of the volcano. A few days later, reporter Goro Maki is sailing in the area and finds the vessel intact but deserted. As he explores the vessel, he finds all the crew dead except for one young man called Hiroshi Okumura, who has been badly wounded. Suddenly a giant ''Shockirus'' sea louse attacks him but he is saved by Okumura.