Japan is experiencing an unprecedented heat wave that has triggered a massive emergency response, with authorities recording the highest number of heatstroke cases in years and temperatures exceeding 40°C in multiple regions. Foreign residents should take immediate precautions as experts warn that consecutive days of extreme heat create cumulative health risks. According to NHK, temperatures reached 40°C or above—classified as "gokusho-bi" (extreme heat days)—in Mie, Shizuoka, and Gifu prefectures on July 22, 2026. Forecasters predict similar conditions will continue, with Nagoya, Kyoto, and Kofu expected to experience extreme heat days as well. Tokyo recorded 36.1°C, marking its third consecutive day of intense heat above 35°C. The emergency response has been staggering. The Tokyo Fire Department reported that 382 people were transported to hospitals for heatstroke on July 22 alone—the highest single-day count since 2022. Tragically, one woman in her 70s died from heat-related complications. The previous day saw 287 emergency transports in Tokyo, ranging in age from 3 to 103 years old, representing the highest daily figure for 2026. Nationally, the situation is equally alarming. The Fire and Disaster Management Agency reported that over 10,000 people were transported for heatstroke during the week ending July 19—the first time weekly numbers exceeded 10,000 this year and more than double the previous week's total. This sharp increase has prompted authorities to issue severe warnings about heat-related health risks. The extreme conditions have disrupted normal activities across Japan. A professional baseball farm team game between the Chiba Lotte Marines and Orix Buffaloes in Saitama was cancelled at noon on July 22 after multiple Lotte players showed symptoms of heatstroke. Officials cited player and spectator safety concerns, with Saitama experiencing dangerously high afternoon temperatures. Experts are warning about a particularly dangerous phenomenon affecting foreign residents and Japanese citizens alike. According to specialists studying heatstroke risks interviewed by NHK, consecutive days of severe heat cause cumulative dehydration that progressively increases health dangers. This "dehydration accumulation" means that even if you felt fine on the first hot day, your risk increases significantly with each subsequent day of extreme temperatures. Elderly residents face the highest risk, but the age range of emergency transports—from young children to centenarians—demonstrates that no one is immune. Medical professionals emphasize that older adults may not feel thirsty even when dangerously dehydrated, making conscious, regular fluid intake essential. For foreign residents, understanding the severity classifications is crucial. Japan uses specific terminology: "moushō-bi" refers to days with temperatures of 35°C or above, while "gokusho-bi" indicates the more dangerous 40°C threshold. When authorities describe conditions as "saigai-kyū" (disaster-level), this signals that heat itself is being treated as a natural disaster requiring emergency protocols. Practical prevention measures are essential. Stay indoors during peak heat hours, typically between 11 AM and 4 PM. Use air conditioning without hesitation—electricity costs are minimal compared to hospitalization expenses. Drink water regularly throughout the day, even without feeling thirsty, aiming for at least 1.2 liters daily, and more if working or exercising. Avoid alcohol and caffeine, which accelerate dehydration. Workplace safety has become a critical concern, particularly for foreign workers in construction, agriculture, and outdoor industries. Employers are legally required to provide adequate rest periods, hydration access, and shaded areas. If your workplace lacks these protections, you can contact local labor standards offices (rōdō kijun kantoku-sho) for assistance. As climate patterns shift, these extreme heat events are expected to become more frequent. Foreign residents should familiarize themselves with emergency numbers—119 for ambulances—and recognize heatstroke symptoms: dizziness, nausea, headache, confusion, and cessation of sweating despite heat. Early intervention can prevent serious complications or death. This summer's record-breaking temperatures serve as a stark reminder that heat preparedness is no longer optional but essential for safe living in Japan.