That really depends on what you are planning to do.
How much fuuzoku allowance you need in the budget?
As for living expenses besides rent, it also depends on how much luxury you want. I don’t think the rate of the yen matters in this case. If anything, prices have been more stable here than in the west, although people on a tight budget do complain about the rising cost of living.
I’d say for a basic income, the rent being one third of your budget is the guideline like pretty much anywhere else..
