The variant was present in airport exams on a person in his 40s, a girl in her 30s and two teenagers, the ministry stated Sunday.
Japan is working with different nations, the WHO and different medical consultants to analyse the brand new model of the virus.
The person who examined optimistic had no signs upon arrival however was hospitalised after his respiratory turned tough.
The girl suffered complications, one teen had a fever, whereas the opposite teen had no signs, in accordance with the ministry.
Japan has declared a state of emergency for the Tokyo space, which kicked in Friday, asking eating places and bars to shut at 8pm. Some have complained that is not sufficient, noting practice stations and eateries are nonetheless packed, together with at evening.
Japan has had about 4,000 deaths associated to Covid-19 to this point, and greater than 280,000 confirmed instances.