Useful guidance in case of emergency while traveling in Japan
You can get some useful guidance in case of emergency, including coronavirus matters.
https://www.jnto.go.jp/emergency/eng/mi_guide.html
If you need any help such as hotel cancelation, insurance information, and medical care, call “Japan Visitor Hotline” below.
■Phone number from Japan: 050-3816-2787
Japan National Tourism Organization (JNTO) operates a visitor hotline 24 hours a day, 365 days a year. Call for tourist information or assistance in the case of accidents and emergencies including novel coronavirus. Support is available in English, Chinese, Korean and Japanese.
*quoted from: JNTO coronavirus advisory information
Above adress contains many useful links, as well.