It were the Americans, instead of the Chinese, who defeated the Japanese in 1945 and ended both the Sino-Japanese War (1937-1945) and the Second World War (1941-1945).

The US army defeated the Japanese by gaining control over the waters surrounding Japan, cutting off all imports to Japan; as a result, the Japanese domestic industry which supplied weaponry to the Japanese army came to a halt.

Also, the US army defeated the Japanese by bombing Japanese cities heavily, and in consequence Japan suffered heavy casualties; the air strike was climaxed by the two American nuclear attacks on Japan in mid August 1945, forcing the Japanese to surrender unconditionally.

Although plenty Japanese servicemen were killed by the Chinese troops during the Sino-Japanese War (1937-1945), that was not the cause of the Japanese defeat in the War.