I read that the Japanese military had a plan for the genocide of Australia’s population if they had conquered it. They had a process where they would remove the nutritional food value from rice. Then feed that to the Australians over time starving them to death by denying them nutrition.
One thing I can’t get a good explanation of is what made the Japanese military so brutal. (The samurai culture explanation is too simple!). During the Russo-Japanese War - 1905 the Japanese captured large numbers of Russians. I can’t find any examples of ill-treatment of the Russians. In WWI Japan was on the side of the Allies, they captured a few Germans - military & civilians when they seized German possessions in China & the Pacific. Again no stories of ill-treatment! What changed? I have read about the re-emphasize of the Emperor Cult as well as Shinto but it all seemed too small & disorganized to be effective in instituting that kind of change.
Since 1920s, the expansion of the Empire of Japan was mainly pushed by middle-level military officials and right wing fascist civil groups. They were radical, unscrupulous and defiant, conducted a series of coups and assassinations to intimidate civil government and military leaders.