All the money in Japan goes to pay the debt since the bubble burst 2½ decades ago. Hence the deflation. It feeds on itself.
The true reason for the Japanese decline? Plaza Accords.
What I remember of the Plaza Accords, there should be two main points.
1) adjust the trade balance which was deeply in favour of Japan at the time
2) agreement towards new levels for the exchange rates between USD, Yen, Euro.
We have to remember, that at that time Japan had two bubbles. ONE in the real estate market. TWO in the stock market.
When the Plaza Accords went into effect, the exchange rate strengthening of the Yen, burst the twin bubbles in Japan of real estate and the stock market, ushering in deflationary forces, which in turn produced the lost decades.
If people are depressed in Japan, who can blame them? The Japanese fighting deflation and economy has been stagnant for 20 plus years.
That is not to say the Plaza Accords did anything for the trade balance, Japan's trade surpluses remained.
The only thing I can really comment on the cultural aspects of this ancient history, is that Japan got outsmarted by the Americans with the Plaza Accords.
Then later, China became the world's second largest economy blowing by Japan. China had outsmarted Japan.
Since America cannot get any traction on China in the trade war and tech war today, clearly in Japanese eyes, China is going to outsmart the Americans.
What the Japanese hold dear and true, that is proving to be a false god. Little wonder if culturally they having their daddy issues.