Remember, as Japan you have like 20 planes from start you can put on carriers. This is the key. If you position wisely you dont ned to buy any fighters for the first 5 or 6 rounds. At the same time you shoud by at lest 5 carriers. But your fleet also need a few destroyers, but not more than the original 4. Any extra navy should be subs. The more the better.
So ideally at end of round 5 you have like 8 carriers, 2 bb, 2 cr, 4 dest, 4 subs and 5 trannies
America cant push you away noe and you should be making around 65 every round. You have spent like 140 ipc on navy and you have made a total of about 200. This give 60 for facilities and inf in china. Buy 1 or 2 factories or 1 factory and a navy base. Depending on situation. Ideally just 1 factory. Also, dont be to afraid of the far east russians.