Over 200 years ago, Japan’s finest poets would gripe about the unbearable heat of midsummer. Issa Kobayashi, in particular, could haiku perfectly on the pathetic gratitude he felt for three cooling raindrops.

But in an era of record temperatures, nationwide alerts to remain indoors and surging hospitalisations, lyrical complaint is no longer quite enough. Japan is sweltering as never before, people are dying and insurers are innovating.

Few countries have been spared temperature extremes in recent years, and many studies predict the frequency of such events will only rise worldwide. But Japan, as an advanced economy with an ever more economically dented middle class, a deepening labour shortage and the world’s most aged population, has entered a distinctive version of the heat crisis with warnings that should echo globally. The recent Japanese invention of heatstroke insurance, while eye-catching as a piece of commercial innovation, tells an unsettling story about those it will cover.