The Japan National Tourism Organization has a hotline providing information about the coronavirus in English, Chinese and Korean, 24 hours a day.

050-3816-2787  (Overseas: +81-50-3816-2787) 

If you have cold symptoms or a fever, stay at home. If you need to see a doctor, call the hospital/clinic first before going for a visit.  If the cold symptoms or a fever of 37.5℃ continues for four days or more, call your local public Health Center. (in Japanese)
For inquiries on coronavirus, you can also call:

Tel: 03-5320-4509 (TMG)
Hours: 9:00-21:00 (includes weekends/holidays

Tel: 0120-565653 (Ministry of Health, Labor and Welfare)
Hours: 9:00-21:00 (includes weekends/holidays)  

Shibuya Ward Coronavirus Consultation Center
Tel: 03-3463-3650 (weekdays 8:30 am to 17:15)
Tel: 03-03-5320-4592 (weekdays 17:00~9:00am, all day on Sat,Sun and holidays)

Minato Ward Coronavirus Consultation Center

 Tel: 03-3455-4461 (weekdays 8:30 am to 17:15)