A point on fuel consumption...
Using nuclear power and Japan's amazingly efficient rail system, you could effectively cause people to not use cars; then you can further refine all of the gasoline into Jet-A (which would be a process, but can be done with a basic chemistry set).
The choke point would be diesel fuel for farm and military equipment... but a monkey cam refine diesel put of crude oil, and they started drilling before their National Strategic Reserves ran out (assumedly).
There would be hard choices, sure; people who worked in sectors of the economy that no longer matter (why have a currency exchange without the USA?) would need to find new jobs, and the government would probably want them working on a Farm Board (go wiki that) or some other similar thing.
And NEETs and Hikikimori would basically be tossed into the JSDF or out to a Farm... or just out to die. (No, I'm not in favor of that)