Thoughts on KJF
Despite the initial advantage of having remaining fleet after Pearl Harbour its v. difficult for Japan.
If you push hard on land, the US fleet quickly outnumbers you at sea. If you throw everything into the Pacific, you never make up the income deficit you start the game with and its only a matter of time before a massive sea battle takes you out.
On the plus side, while Japan is struggling to get by Germany may be doing well- as Jennifer says; if all you do is slow the US, the Germans may get to Moscow in time.
The single worst thing that can happen is that Tokyo comes under siege since then you have to waste IPCs building inf there. So you have to match US naval build, exploiting the defender advantage enjoyed by carriers and FTRs.
Given Japan is poorer than the US you have to make savings somehow and the obvious one is to use island inf for your mainland campaign instead of buying them. So build a bunch of TRNs and start getting them to the mainland asap, Once the US is strong enough to get past the Jap fleet then it wont make much difference whether there’s inf on them or not.
Because its so slow getting them over you probably wont make any headway in Asia if the Allies put an IC in Calcutta or Singkaing and you’ll start to shrink if they put both ICs there.
If you can grab Calcutta early enough to stop an IC build that helps because then you either get a clear run at Asia or face US IC build which detracts from their Naval effort. On the other hand, letting the Brits build 3 inf a go in Calcutta does detract from any bothersome behaviour around German shores, allowing a straightforward infantry push at Moscow which if done efficiently is going to win eventually. Of course Tokyo may fall soon afterwards…
If you play with the enhanced rules then the Banzai national advantage, Russian-Japan treaty, US reinforced carriers Tokyo Express and Yamamoto battleships change things a bit.