A US breakdown also puts some very tempting territories up for grabs by the Japanese. Hawaii for example was a very strategic piece of territory, even after annexation by the US. Although American ownership of the Hawaiian islands may have dampened and settled the issues with the British and the Japanese for a while, with the full force of the US having departed from the world as a whole that leaves Hawaii up for grabs, and Japan would certainly be gunning for ownership of that. It may not be an economic salve for Japan, but it would be a military advantage.

We can also go around to discuss World War 2 industrialization. While Roosevelt's New Deal started to make the Depression better by putting money into the hands of otherwise young and unemployed workers, going to war was a quick reboot for American industry and got everyone back to work; including women. While a series of minor conflicts may imply a debt, over the long term for Japan it might force their industry to rebound as they begin producing industrial goods on a larger scale and getting their own people to work, thus giving them money to spend on the Japanese economy, and getting wheels turning again. And even outside of China there's plenty of punching-bag nations for a country with as well a developed navy as Japan's to invade. The Philippines, Indonesia, Indochina, and very possibly clear to New Zealand and Australia if they feel ambitious.

I think there'd even be known oil reserves in or around Malaysia if they can kick out the British.

And the benefit of the world being in depression as it is, is that a lot of everything is cheap which is why no one is really producing anymore because it's not worth the effort to drill for oil when it's sold for ten cents a gallon; while oil producers may be suffering chronic shrinkage to compensate, a nation like Japan could still buy it from other producers at low prices if they're willing to suffer short-term debt.

And while it would make sense for Japan to continue to hole Manchuria and Northern China as they did, I suppose it's inevitable if the KMT got their shit together and decided to not just play a guerrilla war to stretch the Japanese thin. The game under Chiang kai-Shek was to keep pulling the Japanese thin until the entire Imperial Army was forced to post sentries at every culvert and any one of the thousands of bridges that could fall in their territory, by which point the Japanese could no longer advance and it was just then a series of poking and prodding until most of them are chewed up and they were forced back out, slowly.