You can get some useful guidance in case of emergency, including coronavirus matters.
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.