Scientists create amphibious supersoldiers and detonate a nuclear bomb. In the midst of the fallout, a monster arrives, leaving Japan defenseless. Mankind's only hope is an irradiated water goblin with death on its mind.

The kappa, in Japanese folklore, are water goblins that are closely associated with a certain town in the country. Unfortunately, the area is also home to a militant splinter group of researchers dedicated to developing amphibious super soldiers based on the kappa of legends. When their experiment's result in murder by some escapees, the appearance of an actual kappa, and the triggering of an atomic bomb, the consequences are of epic proportions.—Anonymous