Sixty-six more people on board a quarantined cruise ship at Yokohama Port have been confirmed to be infected with the coronavirus. That brings the total number of cases on the vessel to 136.
People with confirmed infections will be hospitalized, as were cases discovered earlier.
The large number of patients means some will be treated locally while others will be sent to nearby prefectures.
The health ministry will continue to quarantine around 3,600 passengers and crew who remain on the liner until February 19.
But the top government spokesperson says it will be difficult to test everyone on the ship.
Chief Cabinet Secretary Yoshihide Suga said, "We will prioritize people with symptoms, such as high fever. Older people will also be given priority."
The Diamond Princess has been under quarantine for a week. It left Yokohama last month and made stops in southern Japan, Hong Kong, Vietnam and Taiwan before its return.
The ship caught the attention of medical authorities when an 80-year-old passenger tested positive for the virus after disembarking in his home city of Hong Kong.