Nabi Tajima, who was born August 4, 1900, died around 8:00 pm (1100 GMT) Saturday at a hospital on her native Kikai Island in Kagoshima region, according to Susumu Yoshiyuki, a health and welfare official.
Tajima, who became the oldest woman in Japan in September 2015, could have been the oldest person in the world since Violet Brown of Jamaica died in September 2017 at age 117, Japanese media said.
Since Brown’s death, Guinness World Records has been investigating who is the oldest person in the world and was yet to recognise Tajima as such.
The oldest man in the world is 112-year-old Masazo Nonaka of Japan, the organisation announced on April 10.
“Ms Tajima was living at a nursing centre for the elderly. In January, she became weaker, so she was taken to a local hospital,” Yoshiyuki told AFP.
“She died there (Saturday) due to her advanced age,” he said.
Japan is known for the longevity of its people and has been home to several oldest title holders.
There are around 68,000 people aged 100 or older in the country, the government said last year.