Just thinking: Don't have Britain/France fight the Nazis at all and have a straight match-up of Germany vs. USSR. How? Ribbentrop seems to be blamed for messing up the German-British relationship. Get rid of him (how's up to you, simple accident or just send someone else as the ambassador) and the British might - just - tolerate the invasion of Poland (unlikely, I know). That puts the USSR and the Nazis side-by-side. Have a few more Soviet spies exposed in1940/41 in the US & UK, less enthusiasm for the USSR as a whole when Barbarossa starts roughly on schedule so reduced/delayed/no material support from the west. Then the kicker; Stalin, the 60+ heavy smoker/drinker under stress from leading the fight for the USSR, has a stroke/heart attack at just the time they need unity. The resulting infighting gives the Nazis enough of a chance to ....... "win"?, for a given value of win.
No idea how to have the Japanese win though.
No idea how to have the Japanese win though.