The Japanese had planned to use their submarines for a number of different tasks before, during and after the attack. Prior to the bombers and fighter planes arriving from the Japanese aircraft carriers to the north, these submarines were to scout and penetrate the defenses of Pearl Harbor. Once the attack from the air started, they were to release their torpedos at prime targets and escape back out the channel.
After the attack, these submarines were to station themselves in pre-designated spots of the islands to pick-up any pilots who couldn’t make it back to their carriers due to fuel or mechanical issues. One such pilot landed on Niihau (a small Hawaiian island near Kauai). Unfortunately for that Japanese pilot, his submarine had long left it’s position, stranding him there.