Why was such savagery inflicted on a nation the Japanese once regarded as their main source of cultural inspiration, their Rome and Greece?

The Japanese invasion of China lasted from 1931 to 1945, immediately before and during World War II. During this dark period in modern Asian history, the Japanese military machine was motivated by an uncontrollable desire for aggression, expansion and imperialism. The brutalities and atrocities committed by the Japanese military in China and elsewhere in Asia finally ended with destruction on Japanese soil, which to this day is remembered as the atomic bombing of Hiroshima and Nagasaki in August, 1945. The victims of the Japanese militarists' aggression included the peoples of China, Korea, the Philippines, other south East Asian countries, United States, and Japan herself. However, those which seem to have suffered the greatest and most questionable actions by the Japanese were the civilians occupying Nanjing...