The Chinese certainly did the heavy lifting losing 19,600,000 citizens, 10,000,000 military casualties , occupying 34 Japanese Imperial troops who could have fought elsewhere ...the Japanese army was over 6,000,000 at its height...the Chinese Nationalist Army 14,000,000 (simultaneously  also fighting the Chinese Communist  army of 400,000)  killing nearly 400,000 Japanese troops.....with the US army nearly 8,000,000 at the time with 3,600,000 in the Pacific region.

Australia had 600,000 , the U.K. 400,000, British Indian army 2,000,000 fighting on their various fronts in SE Asia.