Medical emergency
Call 119 and say 'kyuukyuu desu' (it's an emergency). Ambulances in Japan are free; you pay only for hospital treatment. Bring your passport and travel insurance details — most hospitals ask for payment on the day and you claim it back later.
Feeling ill but not in danger
Ask your hotel to call a nearby clinic, or use the JNTO medical institution search for facilities with English-speaking staff. Pharmacies handle minor issues, but Japanese over-the-counter medicine is milder than you may expect.
Lost passport
Report it at the nearest police box first and keep the report slip — your embassy will ask for it. Then contact your embassy or consulate in Tokyo, Osaka or Fukuoka for an emergency travel document.
Earthquake or typhoon
Follow the Safety tips app and hotel staff. Indoors: stay away from windows, protect your head, do not run outside. Trains stop for safety and restart after inspection — that is normal, not a crisis.
Lost, drunk or stranded after the last train
A koban will help you get home safely; that is part of their job. Otherwise a taxi, a 24-hour café or a capsule hotel near the station will cover the night.