this is my open attack phase with japan. 1. Sink the american fleet as much of it as you can anways, i can usually bring three fighters, a bomber, a sub a carrier and two battleships. this pretty much destroys the american fleet in hawaii and if you are playing by the combined american fleet ruling then it is possible to destroy the entire US navy. Do not use the transports in the attack as japan needs them later. 2. Invade alaska. Use two inf from the japanese home island to hit alaska. this puts the US and UK on the defensive and starts them siphoning off to protect their assests in nor America. 3. hit india and into chinese territory. again take as many ipcs a turn as possible.
reinforce where necessary during non-combat. DO NOT reinforce alaska. you will not be able to hold it and allow america to build the factory there and save yourself the money.
my first turn by for japan is a factory and a transport. the factory goes into the phillipines and the transport into japan. the trick to this campaign is to build a transport and as many inf as possible every turn and keep them moving onto the mainland.
this is how i beat the american in three straight games by not allowing them access to the factory i am using to resupply my mainland asian forces they cannot take it and use it against me.