A 30-year-old Chinese national who had previously travelled to Wuhan developed a fever on 3 January and subsequently returned to Japan on 6 January. He tested positive during a hospital admission between 10 and 15 January. He had not visited the Huanan Seafood Wholesale Market, but possibly had close contact with an affected person in Wuhan.
On 24 January, a second case was confirmed via a Chinese national who visited from Wuhan. On 25 January, the third case was confirmed in a woman from Wuhan.
Japan has been taking extra precautions, due to the upcoming 2020 Summer Olympics being held in Tokyo. Despite this, on 28 January, the fifth, sixth and seventh cases were confirmed in Japan, including a man who has not visited Wuhan. This man was reported to be a tour bus driver who had driven a group from Wuhan earlier in January. The guide of the group has also been confirmed positive to the virus. On 29 January, a Chinese man and woman in their 40s were tested to be positive for the coronavirus in Aichi and in Hokkaido.
On 30 January, it was announced that three Japanese nationals who arrived at Haneda after being evacuated from Wuhan tested positive. Three other cases were confirmed on the same day. Prime Minister Shinzo Abe announced two Japanese nationals who came back via Haneda refused requests to be further tested and said that officials cannot legally force them to do it. It was announced on 31 January that the two had relented.
From 3 February, Japan will not admit anyone who has history of travelling to and from Hubei Province or has a Chinese passport officially issued to Hubei. In addition, non-Japanese travellers are required to fill out health declaration questionnaires on whether they have (or will) travelled to Hubei within 14 days.
On 6 February, the Ministry of Health, Labour and Welfare confirmed that 20 passengers on the Diamond Princess were diagnosed to be positive for the virus. Japan Coast Guard officers will be responsible for transporting the infected to nearby hospitals from the port of Yokohama. A Hong Kong national had previously boarded the ship on a cruise, who was tested to be positive for the virus.