I think that the overall strategy is the same for each game, it being to put pressure on Russia. However, there are multiple avenues in which to do this. Japan must decide how to get to Moscow. It can go by land or sea.
Land Options:
North Asia thru Siberia
Middle Asia thru China
South Asia thru India
Sea Options:
Pipeline from Japan to main land
Amphibious assault India
Take Suez Canal and up to Caucus
There are also the decisions about I.C. and air support.
Build I.Cs on mainland options
Kwangtung
Manchuria
F.I.C.
India (after captured from U.K.)
Air support options.
Bombers to strategic bomb Russia
Bombers to strategic bomb U.K.
Fighters to defend Germany
Fighters and Bombers to fly to Europe and then disrupt U.K. and U.S. convoys
Then there is also the decision about not going after Russia. Other options (not the best) could be:
Go after West U.S. early and tie up materials
Go After Alaska
Go After Africa
So, I think that Japan has the same overall objective each time, but the execution can be very different.