I agree, even after writing 2 scenarios that might work, looking back and looking at Assassin Creed lore (if you want to call it that), Japan is almost unviable. Japan was secluded for 300 odd years, with very little foriegn influence and technology going through it. Plus going back to the Shimbara rebellion, that is the only time where christianity ever had a stand in Japan. To much work and changing history to make Japan viable.
I would still like China though as, that does have viability to it especially after the opium wars where Britian essentially controlled it. It wouldn't be hard as all the pieces are set.
Foreign diplomats are inreality Templar officials, Qing emporer has a piece of eden hidden somewhere which was used once during the mongol invasion and Manchu's rise to power, Assassins learnt of Templar movement and counter to halt and stop their attempts. (I should be a writer for them haha :P )
America does have a similar scenario, moreso due to their direct involvement with Europe (Britain) so I can see why they went this direction
nice share longy999