Japan can do what ever she wants. Germany chose a path, and her neighbors accepted her. Japan insist on denying what she had done, preserve the political parties if in power capable of repeating it and when confronted have people who will try to justify it or change subject as you are doing.
Japan again has a choice and she will have to live with it again. I do agree with you on one thing. If Japan had remain neutral in WW2, Manchuria plus Korea and Taiwan gave her ample resources. She would emerge with the US with intact manufacturing while most of the world’s would be destroyed. Japan would be in position to be the dominant power in Asia without firing a shot and power broker in the Cold War between the US and USSR.
By the time of the Pearl Harbor attack, Japan controlled the entire Chinese coast and a big chunk of the interior, close to a third of China's land mass, and most of its developed areas. If they had merely been patient, what is now China would be a bunch of large Japanese provinces. They got greedy and paid a heavy price.
There's this myth about East Asians being cautious and risk-averse. My impression is that they are degenerate gamblers.
When Japan expanded into China, it was merely emulating what China had done for thousands of years, adding to its territory in times of military strength, which is why China is today the size of a continent. Unfortunately for us (given our alliances with Japan, Korea and the Philippines), China's about to resume its old habit of playing weiqi (Go) off the chessboard, with real men and weaponry in place of stones. When Japan struck at Pearl Harbor, it had 1/9 the GDP of the US. China has 1/2 the GDP and is closing on parity. I think we need to slowly disengage from the area, giving these countries enough time to re-arm so they can build nuclear deterrents and improved conventional capabilities. We lost 100K men during WWII, 40K men in Korea and 60K men in Vietnam. We've donated quite enough blood to the patient. It's time for them to defend themselves.