The AI does not care about the Pacific.

[FlinzP]

Played Japan recently and also noticed how little Allied majors care for Asia. Their puppets try best but eventually they lose all resource rich areas starting to cripple masters. I was surprised that USA didn't try anything at all. Their troops and fleets disappeared. Without support even Australia and India falls. Without resources to boost Allies they hardly can do anything against Germany. As Japan it is easy to start support Axis against USSR. Yet somehow USA feels Africa and Norway are their top priorities. Maybe they like to use already existing naval control rather than create them.

 

[Longshanks51]

My recent Japan game, I declared war on the allies on December 1941, and in a few years I've managed to capture every allied island in the pacific with little to no resistance.

Granted there were UK and US divisions in India so that part wasn't too easy.
Indonesia and the Philippines also had a good number of divisions so that part was fun.
Australia and New Zealand had no divisions whatsoever guarding their mainland.
Meanwhile Germany was struggling against the soviet union and the allies did their Normandy and naval invasion of Italy.

Mexico joined the allies around 1943 so I managed to naval invade them and push up into the US. In 1945 I managed to capitulate the US and Canada.
(Although most of their divisions were in Europe the US still put up a challenging fight on their homeland)
By now the Axis is defeated and Germany is divided. And going to try to island hop from Greenland to Iceland and see if I can invade the UK.

So I've had a mixed bag, but I agree they should really make an effort to defend their islands.

 

[FLUX2226]

Even if Japan loses against China and joins WW2 without puppets, Chinese resources or industry, they still conquer Malaya, the Indies, Australia, NZ and many of the Pacific islands because there's just so little resistance.