It's economy didn't collapse in a total war for the next 3 years, no?
Yes it did. Severe rationing, centralized planning of resource allocation, rigid currency controls, The Zaibatsu capitalist operations were being reduced to socialist planning agencies. Corruption and black marketing. In Mid 1942 Japan was at the top of its military game, yet imports/exports for military operations were insufficient and for industrial purposes had ceased. Factories were running of prewar stockpiled material & where there were no stocks they were shutting down operations. The capture of the Dutch East Indies oil production was hardly noticeable in the home islands, by the end of 1942 planning had began to convert oil power generation plant back to coal as there were still coal shipments available from Manchuria. Conversion was initiated in 1942. French Indo China was a huge rice exporter, but the lack of cargo shipping alone meant rice remained strictly rationed in 1942. John Ellis 'Brute Force' has a long chapter describing the inability to build sufficient cargo ships, war ships, aircraft or train air crew ran straight back to resource shortage at the end of 1942. The details differ between the war & the trajectory of Japans economy without the war, but there are several key general conditions that parallel.
Cargo shipping. in 1940 between 50% & 60% of Japans imports exports were carried on foreign flagged ships. When the embargo Acts froze Japans accounts in the US it foreign flagged carriers could not be paid. The cut off of foreign flagged ships for Japans economy reduced service from over 11 million tons in 1940 to under six million available in the first half of 1942. Without war severe negative cash flow & end of credit in the international banking system creates the same effect. Japans industry and government cant pay for sufficient raw materials, and cant pay for enough transport. It would not matter if the US or Dutch oil companies were allowed to sell petroleum products to Japan. With a increasing negative cash flow and credit collapse Standard Oil or Royal Dutch Shell wont be paid.
Steel: Japans steel industry was dependent on high quality scrap steel from the US & elsewhere. In the 1930s the ship breakingindusty was becoming import for Japan as it provided bulk scrap iron & steel.
Machine tools & alloys needed for manufacturing tools: Yet another sector Japan lacked internal capacity for its needs. Expensive imports were needed & A Europe at war drives up that cost.
In the short run implementing a command economy can extend Japans industrial operations. Thats what they resorted to, even before the Pacific war started. Central planning & free market restrictions were being planned and implemented by 1940. By the end of 1942 free market & capitalist economy had effectively ended in Japan. That could help in a economic collapse scenario, but I don't think that anyone will argue that rigid socialism or defacto Communism would be be any sort of solution to get Japan through a stalemated China War & unservicable debt burden.
My estimates here are strictly that. Perhaps occupied China and Manchuriias industrial development could start paying off from 1941-42 absent the Allied embargoes and war. Even 1943 might not be too late if the profitability is clear to the international banking community. But given the trends through 1940 & the inefficiencies in the Zaibatsu system and general exploitation of occupied Asia I'm not optimistic.