[1] http://en.wikipedia.org/wiki/Article_9_of_the_Constitution_o...
[2] http://en.wikipedia.org/wiki/Occupation_of_Japan#Disarmament
[3] http://en.wikipedia.org/wiki/Japan_Self-Defense_Forces#Defen...
Have a look at the Hyuga class "helicopter carrying destroyer": http://www.jeffhead.com/worldwideaircraftcarriers/16ddh.htm. On thing you notice is that unlike almost every other amphibious assault ship in the world the Hyuga class has an offset island, meaning you can land fixed-wing aircraft. Officially it carries 18 helicopters, but it has everything you need to carry an air wing (range, fuel, ammo, maintenance, and communications). So all they really need to to is fly off the helicopters and fly on some sort of STOL aircraft (like the F-35C) and presto! An aircraft carrier about on par with the British Invincible class.
Recently the Maritime SDF (you know, Navy) got the go-ahead for a "helicopter carrying cruiser", which would be the same thing only bigger, although still officially not an aircraft carrier.
In the case of Japan birthrates have been a subject of concern for at least the last two decades. There are many potential contributing factors, not the least of which is the enormous amount of stress on the average family and the exorbitant cost of living in a megalopolis such as Tokyo; the stress of working long hours and having high expenses is enough to prevent people from having kids and even having a relationship.
Although geopolitically Japan is generally a peaceful society de facto I would argue that that is not necessarily true culturally. And even in the context of geopolitics there is a fair amount of drama in Asia that involves Japan, e.g. between the South Koreans, China, Taiwan, and Japan.
[1] http://en.wikipedia.org/wiki/Honne_and_tatemae