Here is what I am wondering--if Japan would have joined the Central Powers during World War I*, and if the Central Powers (especially Germany) still manage to decisively defeat Russia in this TL's WWI to the point of Russia experiencing revolutions (plural), exhaustion, and collapse and still manage to get an extremely generous peace treaty from Russia with Russian concessions similar to our TL's Brest-Litovsk Treaty, how much concessions from Russia, and specifically which concessions, will Japan get in such a scenario and in such a treaty?
*The U.K. might need to remain neutral for this to occur, due to it being Japan's ally back then; in order for British neutrality in WWI to occur, assume that Germany had somewhat smarter leadership or something and thus provoked the U.K. less.
Also, assume that WWI still occurs in this TL. The timing of WWI in this TL isn't important just as long as Russia is crushed in this TL's WWI as much as it was in our TL's WWI.
Anyway, any thoughts on this?