Kokushobi Guide
A Japan heat-safety companion for travelers and residents that says when it's safe to be outside, where the nearest cool spots are, and how to dodge becoming a heatstroke statistic.
Tourists and residents in Japan navigating dangerous summer heat
- Hour-by-hour 'safe-to-walk' forecast using WBGT, humidity, and sun exposure
- Cool-spot finder for malls, museums, covered arcades, and AC-cooled train stations
- Hydration and shade-rest reminders with push notifications tuned to age and activity
- Family mode that tracks kids and elderly relatives with location-based heat alerts
Tokyo hit a record 453 hospitalizations in one day, 'kokushobi' was just coined for 40°C+ days, and heat alerts now cover nearly all of Japan — peak traveler and resident anxiety.
Kokushobi was officially coined by JMA in April 2026 with 478k votes in naming contest; BBC, Guardian, Tokyo Weekender, Mainichi all covered; multiple safety guides written specifically for foreign tourists facing summer heat.Japan Coins New Term 'Kokushobi' for 'Brutally Hot' 40°C Days ↗Heatstroke in Japan: Prevention & Emergency Guide for Tourists ↗
Existing competitors are fragmented: official JTA 'Safety tips' app covers disasters generically, Summia Heat Alert and HeatAlert.app target WBGT but not tourist-specific safe-time/cool-spot workflows; no single tourist-focused heat companion dominates.Safety tips for travelers ↗Summia Heat Alert - Apps on Google Play ↗HeatAlert: Heat Stress Index ↗
Hard to monetize: JTA 'Safety tips' and env.go.jp WBGT data are free government services; existing heat apps (Summia, HeatAlert) appear free; travelers can rely on blog guides, leaving limited willingness-to-pay for a paid heat-safety companion.Safety tips for travelers ↗Special Heat Stroke Alert ・ Heat Stroke Alert - env.go.jp ↗
Climate trend is strong and decades-long (Japan's hottest summer on record, expanding heat-alert coverage), but product usefulness is gated to roughly May–September, limiting year-round engagement.Japan temperatures soar over 40C, marking first 'cruelly hot day' ↗
Building is tractable: official WBGT API exists at env.go.jp, weather data is plentiful, but curating tourist-relevant cool-spot POIs (malls, museums, stations) across Japan requires significant manual mapping work.Heat Illness Prevention Information: Current WBGT and Forecast ↗