Chief Cabinet Secretary Suga Yoshihide says Japan is monitoring the situation in Kaesong.
He said his government is working closely with the United States and South Korea to gather and analyze information on the incident.
Tokyo's governor says the city remains at a critical phase in its battle to prevent an explosive rise in coronavirus infections, and that the situation is getting more serious.
Koike Yuriko gave the assessment at a news conference on Friday. She said people should avoid closed, crowded places and close-contact settings.
Prime Minister Shinzo Abe says Japan is not in a situation where he needs to declare a state of emergency based on a law that came into effect on Saturday to tackle the spread of the new coronavirus.
Speaking to reporters on Saturday, Abe said cases in Japan are contained compared to other countries.