A couple of points to state on the record for plausibility
- Japan was never a full member of the Axis Alliance
- Japan refused to help in Operation Barbarossa
- Japan did not consult Hitler over Pearl Harbor
- A Japanese (non-Aryan) World Power in the long term did not fit the Nazi Worldview
- Japan was a threat to British Rule (Aryan Rule) in India (Again, according to Nazi craziness) which Hitler wanted to preserve.
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Those things being said, what if Hitler, after Japan's suprise attack on America issues a DOW on the "yellow menace" in the East and then preceded to attempt to re-establish diplomatic & economic ties with their old Chinese ally, Chaing-Kai
How do the Wallies react? Can ceasefire negotiations plausbiliy happen on the Western Front?