Japan's second-hand boom is not caused by a sudden spiritual uplift to not be mottainai, but by 20-30 years of economic stagnation and a growing underclass of poorly paid temp workers who can't afford anything else.
That's without question a big part of the story. In 30 years they've gone from having a higher GDP per capita than the US, to being in a position where they have to increase it by ~57% to catch up. It's roughly where it was in 1993 in USD terms, before adjusting for inflation.
The US is well known for having a high output economy. It took the US until 2005 to catch up to where Japan's GDP was at in 1995 per capita (~$43,000). Or to lend another perspective, their GDP per capita in 1995 was about 40% higher than Germany, and now it's below Germany.
It would probably be fair to say they've seen a real loss of at least 1/3 of their standard of living in a quarter century. It was artificially inflated from the asset bubbles they had in the late 1980s and early 1990s, however that's still a painful drop and a long stretch of time to stagnate.
They went through truly massive public works spending that entirely failed to spark big economic productivity gains or greater output. A savings rate that dropped to nearly zero. A public debt so high it's 2x that of the US as a percentage of GDP. Debasing the Yen became their only means to try to escape the towering debt, once the population could no longer afford to lend the government any more money (as the savings rate plunged). With the Yen debasement went their extraordinary standard of living. The challenging part, is that they're nowhere near done needing to debase the Yen, they still can't afford their debt at all.
As part of their magic central bank economy solution, the BOJ has even taken to juicing the stock market directly by slowly nationalizing it (buying up nearly 4% of the market directly).
