I am not sure of the distinction. Do they not spend funds on offensive weapons? Do they have fighter planes, long range bombers? Japan is entitled to defend its borders as any other nation. Why is their defense not military as you stated?
The Japanses constitution limits its forces to a "self defense" role. They have given that term a fairly broad reading, however, with Japanese troops having taken part in 'self defense' missions in Iraq. Long range bombers and ballistic missiles would definitely be out.
Their naval (sorry, make that 'maritime self defense') forces are heavy in anti - air and anti - submarine capabilities, much weaker in shore bombardment assets. They do, however, see protection of strategic sea lanes within the 'self defense' sphere.