According to the NHK broadcaster, all those isolated came in contact with the patient who was taken to a hospital with all the typical MERS symptoms.
The MERS outbreak began in South Korea in May, and killed 36 people. In July, the country declared a "de facto end" to the outbreak.
The virus is transmitted from camels to people, with limited human-to-human transmission, according to the World Health Organization (WHO). The infection causes such symptoms as fever, cough and shortness of breath.
There is currently no approved vaccine for MERS. People with chronic illnesses or a weak immune system are at a higher risk of contracting the viral respiratory disease, which was first reported in 2012 when a Saudi patient died in London.