The Second World War taught Japan valuable lessons. The first—don’t start wars—is an obvious conclusion that has been taken to heart. Other lessons were the result of the wartime Allied air and naval blockade of the country, which brought it to the brink of starvation. For Japan, poor in resources and arable land, to survive the next war, the air and sea lanes must stay open, and for that to happen, Japan must have top-flight air and naval forces.
Japan’s postwar submarine fleet is one of the best in the world. With an authorized total of twenty-two submarines, the Japan Maritime Self Defense Force’s submarine fleet is also one of the largest. Japan builds its own submarines, with the work split between Mitsubishi Heavy Industries and Kawasaki Heavy Industries, both based in the port city of Kobe…..
SOURCE : http://nationalinterest.org/