Ten years ago was near the start of the US real estate bubble. It made excellent sense to buy in 1999, as I did. But one precipitating factor was that the owner of the house I had rented for ten years with no increase in rent had decided to sell all of his ~ 10 rental homes in the San Fernando Valley. The other factor was that I had just started my own company and had almost doubled my income the previous year. I could, at last, afford a house and, after preparing my income tax returns for '98 could painfully see how I needed to have the interest deduction for real estate to capture more of my income for my family.

The US tax code strongly encouraged me to buy a house. But I also worried that, were real estate values to continue to rise, so would most rents, and I did not want to have to move often. Best decision I ever made.

But the last real estate bubble in Japan burst 20 years ago.  It is hard to know if real estate would make sense as an investment, even if you knew you wanted to stay in Japan for another ten to twenty years. If your annual rent is over 75% of what a mortgage payment would be and you were confident you had long term employment, ten years or so, it might make sense.

If long hours at your job are a problem, anything that makes your life easier makes sense. Do it yourself home maintenance probably doesn't qualify there. :-) But saving so that you have options does.  Having two year's worth of income saved would leave you more comfortable changing locations, either within Japan or elsewhere. You might also be able to find a situation that is less demanding of your time, which could allow you to invest more in personal abilities. You could even afford to take off for a year and travel.

In Japan, the problem with the economy for the last 20 years seems to have tilted more to deflation than to inflation. So long as that continues, your savings are appreciating, even if you are not getting much, if any, return on investment. But you might want to diversify in terms of currency exposure. Study the variation of the Yen vs. currencies of countries you might consider investing in, say Brazil, India, the EU and wait until the yen is strong with respect to the target market and buy several somethings that is likely to be there in another ten years in each target economy.

In sum, it is better to have savings, even if they might be eroded in value, than to have none, especially in a crisis.  If diversified, the chance that all of your savings will be worthless is far less than the possibility that they may be very important to you. It may be that a time will come again when economies seem predictable and stable. That will be a much better opportunity if you have savings than if you don't.  But I would spend a portion of that surplus on yourself, on vacations, personal conveniences and smaller pleasures as well.

"It is not necessary to have hope in order to persevere."