Video report by ITV News Correspondent Juliet Bremner
The son of quarantined cruise ship Briton David Abel said his dad has "given up hope".
Stephen Abel has been talking daily to father David and mother Sally on board the Diamond Princess and told ITV News he has seen a "huge change" since the pair tested positive for the coronavirus on Tuesday.
He has also said he fears he is beginning to see signs of dementia in his father.
He said: "My dad has kind of given up hope. Listening to him is very, very upsetting because he's a very, very positive guy and so I've seen a huge change in him.
"But then my mum's turning around a little bit and she's coming up with some added strength."
Visibly upset, Stephen said his father's other health issues are making matters worse for them as they prepare for a six-hour coach trip to a facility in Japan on Thursday.
"He said things today, which make me know that he doesn't think he's coming back because he has his health issues, his diabetes, he's got a tooth infection, he's not eating," he said.
"I was actually watching him heave today he had to give the phone to my mum."
Four Britons on board the cruise ship have tested positive for the coronavirus.
The Foreign Office confirmed the figure to ITV News as hundreds begin leaving the ship, which is docked off the coast of Japan.
Results are still pending for some passengers who had been tested for the coronavirus that has infected tens of thousands of people in China and more than 540 on the ship.
Some passengers said on Twitter they received health check forms asking if they had symptoms such as a headache, fever or coughing.
Plans are being put in place by the UK government to evacuate Britons who were stranded on the cruise ship.
The Foreign Office said they were working to evacuate Britons back to the UK "as soon as possible".
They said: "We hope the flight will be later this week, subject to permissions from the Japanese authorities."
David Abel does not believe he will be on a planned evacuation flight to the UK after he and his wife fear they tested positive for the virus.
But he said in a YouTube video on Wednesday: "We've since spoken to a doctor that speaks English, and we've had to really press hard for that, and it has been confirmed by him we are both positive.
"We are going to a hostel because there isn't a hospital bed anywhere around. So, we're going to a hostel and in four or five days we'll be removed from the hostel and put into a hospital, where we will receive treatment.
"So I can't see that there's going to be any way we're on that flight to the UK."
Passengers who tested negative and had no symptoms still had to have their body temperature checked before leaving.
Japanese soldiers helped escort some passengers, including an elderly man in a wheelchair who wore a face mask and held a cane.
Some passengers apparently called taxis to get home. Others boarded buses to be transported to train stations.
Some people still in their ship cabins waved farewell from their balconies to those who’d already disembarked.
“I’m a bit concerned if I’m okay to get off the ship, but it was getting very difficult physically,” a 77-year-old man from Saitama, near Tokyo, who got off with his wife, told Kyodo News.
“For now, we just want to celebrate.”
About 500 passengers were expected to leave on Wednesday.
Japanese officials will spend several days evacuating some 2,000 others who were kept aboard the ship at the Yokohama port near Tokyo after one passenger who departed the Diamond Princess earlier in Hong Kong was found to have the virus.
The ship, which some experts have called a perfect virus incubator, has become the site of the most infections outside of China, where the illness named Covid-19 emerged late last year.
As of Tuesday, 542 cases have been identified among the original 3,711 people on the ship.
Even though Japanese officials insist the number of infected patients is levelling off, dozens of new cases on the ship continue to mount daily.
On Tuesday, 88 people tested positive; a day earlier 99 others were found to have been infected.
Crew members, who couldn’t be confined to their rooms over the last two weeks because they were working, are expected to stay on the ship.
Chief Cabinet Secretary Yoshihide Suga defended Japan’s handling of the quarantine.
“In the beginning, the United States expressed gratitude for the Japanese side. And there are many Americans who chose to stay on the ship,” Suga said.
Japanese health officials said the 14-day quarantine on the ship was adequate, noting all but one of more than 500 Japanese returnees from the epicentre of the virus in China who initially tested negative were found to be virus-free at the end of their 14-day quarantine.
Those officials also defended precautions taken on the ship.
Some 1,000 crew members were told to wear surgical masks, wash their hands, use disinfectant sprays and stop operations at restaurants, bars and other entertainment areas after February 5, when the first group of 10 infections was reported and the start of the 14-day quarantine announced.
Passengers were instructed to stay in their cabins and not walk around or contact other passengers. Those in windowless cabins could go out on the deck for about an hour each day.
The quarantine was largely for passengers, since crew members kept sharing double rooms and continued to serve guests by delivering food, letters, towels and amenities, and entering passenger cabins for cleaning.