Jerry A. Baerwitz, Ishirô Honda, Motoyoshi Oda
Heavily alerted American version of Japan's Varan. A prehistoric behemoth is unwittingly awoken from hibernation due to a U.S-Japanese military experiment for economic means on it's watery lair.
In an effort to find an economic means of purifying salt water, a joint U.S.-Japanese military command is set up on an isolated Japanese island where an unusual salt water lake is situated. However, their purifying experiments arouse the prehistoric monster Obaki from hibernation at the lake's bottom, and it proceeds to attack Japan.