It is very simple : in november 1941 (after a partial mobilisation ) the IJA had 2287000 men and the IJN 311OOO = 2598000,and there were still 4680000 reservists . In 1945, the IJN had 1693000 men and the IJA 5500000= 7193000 (most men of the IJA were in Japan) ,losses were 1990000 = a total of 9.2 million . This means that Japan was able to mobilize 6.6 million men during the war,opposed to a loss of 2 million .Thus the Japanese manpower was bigger in 1945 than in 1941,and Japan was not at the end of its manpower : there were several million men in Japan ,thus enough to raise an additional 12 divisions in Manchuria . It is also not proved that the Kwantung Army was weaker in 1945 than in 1941. To prove this, one should compare every unit of 1945 to every unit of 1941. To give as "proof" that in 1945 a division had only 20 % of its authorised (= maximum) number of horses,proves nothing . The German term for authorised strength (Sollstärke) is never used ,one must look at the effective strength (iststärke) : 20 % of the authorised number of horses in 1945 can be higher than 30 % of the authorised strength of horses in 1941, and even if the real number of horses was higher in 1941,this does not prove that the division was weaker than in 1941, because the units of 1941 did not better than the units of 1945 .