Few cities in the developed world can have been put as comprehensively through the wringer as Yubari, on Japan’s northernmost island of Hokkaido and known in its heyday as the capital of coal. From a peak of just shy of 120,000 people in 1960, Yubari’s population plummeted to 21,000 in 1990, the year the last colliery closed and the last miners fled. It has since more than halved again, to below 1