Humanity is plagued with attacks by a race of sea mutants dedicated to eradicating mankind. Our last hope is the Blue Submarine No. 6 and her crew, made up of the best personnel available as they fight for the fate of all mankind.

After surviving another undersea battle with Zorndyke’s forces, the crew of Blue Submarine No. 6 returns to base for repairs. While on base, Tetsu continues to display his trademark lack of concern for authority and continues to annoy Mayumi.