One of the new cases is a woman in her 60s who is a junior high school teacher in Chiba prefecture, east of Tokyo, according to a prefectural government official.
The woman first showed symptoms on Feb 12 and was hospitalised on Feb 19, according to media. She went to work while she had symptoms, so the local government will close her school for two days from Feb 25.
The second case was a woman in her 30s, also in Chiba prefecture, who has been hospitalised but is not showing any symptoms, the prefectural government official said.
There is no relationship between the two women and it is uncertain how either of them got the virus, the official said.
Two more cases, a man in his 60s and a man in his 50s, were also confirmed in Kumamoto prefecture in southern Japan.
In Japan, 99 people have now tested positive for the flu-like illness, which has killed more than 2,300 in mainland China.
Over 600 cases have also been reported on the Diamond Princess cruise ship that has been quarantined off Yokohama for more than two weeks. Two elderly passengers died, taking the total of domestic deaths in Japan from the virus to three.