Japan has recorded its first-ever "kokushobi", or "cruelly hot day", after temperatures in three central cities exceeded 40C on Tuesday. The new classification, introduced by Japan's Meteorological Agency in April, was created to give the public a clearer warning of especially dangerous heat, and its first use comes amid a broader trend of intensifying heatwaves worldwide, with Japan's summers becoming progressively hotter and more hazardous.

Tajimi, Gujo and Toyoda all reached the 40C threshold, with the agency forecasting the heat to persist into next week. Nearly 300 of Japan's 914 observation points also recorded a "moshobi", or day above 35C, on Tuesday, while heatstroke alerts were issued across more than 40 prefectures. The Tokyo Fire Department said 287 people, aged three to 103, were hospitalised for suspected heatstroke on Tuesday alone, the highest daily figure this year, prompting an ambulance overload alert. Last year, a record 1,803 workplace heatstroke cases were reported nationally, of which 19 proved fatal, and Tokyo's government has urged office workers to wear more casual clothing to cope with the heat.