When Japan grabs the money islands, malaya, hong kong, FIC and the philippines its income nearly doubles, with a little push in China - Japan can outporoduce the US. Japan only starts hurting when Japan plans poorly and doesn’t make a massive land grab on its first turn of war with the allies.
To be honest, I’m not sold on the idea that Japan can do all that plus hurt China. That doubled income may not last very long.
Depends on the Chinese player, mainly moving their stacks from air attack range.
However, if the Japanese player is consistent in striking Yunnan, denying China materials, it can be done. Trust me.
The real problem comes if Britain decides to do a can opener with tanks and mechanized infantry.