What happens if a flight is cancelled or delayed significantly on the day of departure to Japan and the passenger has to leave the country after 72 hours?

If the flight after the change is within 96 hours from the date and time of specimen collection,
it is not necessary to obtain the certificate again and you may board the aircraft.
On the other hand, if the time of departure after the change is over 96 hours from the date and
time of specimen collection, you are required to obtain a new certificate from the perspective
of quarantine measures.