Sources such as Basil Collier's "The Second World War: A Military History" list the Japanese forces during the war as being 6 million. My understanding is that the background of these troops is roughly as follows:
Of these 6 million troops, 2 million started the war (1937-41) in China, where they became veterans fighting the Chinese.
After Pearl Harbor, these experienced troops were mostly shipped out to conquer the ASEAN countries (Burma, Philippines, East Indies, etc.), or to defend the Pacific Islands (Saipan, Rabaul, Tarawa, Iwo Jima) against American attack.
Two million formerly "garrison" troops left Japan for China in 1942-43, where they acquired "some" experience in the later stages of the war. These were replaced by a new batch of "garrison" troops with little or no experience.
Is it true that the Allies had "already" fought the most experienced Japanese soldiers on their way across the Pacific, and in the ASEAN countries, and would have been fighting relative "greenhorns" in Japan? Just as they fought Japan's best pilots early in the war and "Kamikaze" caliber fliers in the end?