Admiral Footsu was part of the Imperial Japanese Navy during World War II. In 1944, he was stationed in Kobe, Japan, where he had workers constructing a massive super-sub to use against American ships that would encroach on the waters near Japan.
When the Sub-Mariner attempted to destroy the sub, his soldiers trapped the hero in a net and gassed him. After dehydrating the hero with sun lamps, Footsu ordered the Sub-Mariner to be put in a water tight room while he launched an attack against an American battleship fleet. However, the Sub-Mariner escaped and after Footsu's attack forced the American ships to pull back, Namor forced his way aboard the super-sub.
Battling the soldiers, Namor grabbed Footsu and used him as a human shield to reach the ballast controls. There Namor set off a bomb that caused the super-sub to rapidly fill with water. Namor then fled leaving Footsu and his men to drown aboard the sinking submarine.