A submarine suppose to use to attack on US grounds. This is a Documentary on Japanese Submarine Design to carry 3 to 4 aircraft bomber.
During WWII, Japan deployed two stealth submarines designed to carry aircraft, with the objective of attacking the US west coast. The I-400 and I-401 were covered with a special sonar-absorbing material, equipped with four anti-aircraft guns and carried 3 single-engine aircraft apiece in a water tight tube that measured 11 feet in diameter.