Doctors at a hospital in Yamanashi Prefecture west of Tokyo, say the new coronavirus is likely to have caused meningitis in a male patient in his 20s.
The man had a fever on February 27 and visited different medical institutions on February 28 and March 2, but was not tested for the coronavirus.
The man was found collapsed in his home on Friday and was transported to hospital where he tested positive for the coronavirus.
He is now in intensive care with a fever, pneumonia and meningitis.
Doctors at the hospital say it is extremely rare for the new coronavirus to trigger meningitis.