You have to remember that Japan does not have a true Marine Corp. The only that is near to the concept is the Maritime Self Defense Force (Navy) Naval Infantry. Try not to confuse the concepts.
As I said before, the reason why The Self Defense Force does not have a true Marine Corp is because of the imposed Limitions on Military Capabilities to put itself to a defensive role.
http://www.globalsecurity.org/milita...an/weapons.htm