On June 29, 1940, Foreign Minister Hachirō Arita announced via radio that the Empire of Japan would seek to establish a "
Greater East Asia Co-Prosperity Sphere". What needs to happen, with no PoDs prior* to July of that year, for the Empire of Japan (1) not to collapse, eventually stabilizing relations with the rest of the world in some kind of peace, and (2) take this Imperial Ambition as far as it will go (without violating (1))? This can be seen as a precise version of "How could Japan won WWII?" "Winning" in the main of China isn't
entirely necessary, so long as what remains isn't an existential threat to Japan or her allies -- at the least, Manchuko should survive as a puppet state -- that said, the more invasions of European colonies (like French Indochina) the better,
so long as it doesn't inexorably lead to the downfall of the Empire of Japan and can conceivably lead to some version of the "Co-prosperity Sphere" enduring.
*OK, technically I'm seeing this as part of a larger "Axis Win" TL with an April 1940 PoD in Europe, so if you need the Nazis to do well, I've already got rough ideas on that; point is, if you need to go back further, April of 1940 is the limit (that means, for example, the KMT's
Winter Offensive of said year goes as OTL).