Thanks to @rebelfd and @drannehuang for tweeting about this report in Sankei Shimbun: New type pneumonia confirmed for the first time in Japan Travel history to China and Wuhan. The Google translation:
In Wuhan City, Hubei Province in central China, unexplained cases of pneumonia have been occurring one after another. A positive reaction for pneumonia was reported on Tuesday, officials said. It is the first time a patient has been confirmed in Japan, and the government is expected to consult with relevant ministries and agencies on the same day.
No doubt we'll hear much more about this case.