The crimes of Japan are not so unique or recent that they should have onerous limits on their armed forces. Germany and Britain, whose governments or colonial policies killed many millions of people at various points in history, are allowed to have a real army, thus Japan should also. Japan has legitimate threats nearby including China and South Korea, and should have a right to defend itself as a legitimate democratic nation.
No, Japan does not have a legitimate need to build-up its military forces, because it has not been attacked in years. If it were to be attacked, the United States would come to its defense, because it is the United States that has insisted they do not build up their military.
They must not be allowed to repeat stupid history of imperialism which is more than clearly engraved to all asian countries. Japanese military strength will trigger military race and tension among east and southeast asia, let alone china who has become global powerhouse and already having global tension with US and western countries.