Prices feel like a middle income country, but that is just the Yen sucking. Otherwise it feels very first world.
No it isn't. In purchasing power terms Japan has been, or is about to be overtaken by Poland and Slovakia [1]. This is largely due to demographics and the declining share of the working age population. There is nothing that impoverishes countries more. Gradual decline feels fine for a while, until it doesn't when the bulk of the workforce ages out.
[1]https://marginalrevolution.com/marginalrevolution/2024/07/po...
https://www.pewresearch.org/global/2018/11/12/perceptions-of...
Also, a quick googling suggests both Poland and Japan both have fertility rates around 1.2. Working age of Poland is 65% of the population vs 60% for Japan. So a bit worse.