The world's oldest woman, 115-year-old Koto Okubo from Kawasaki, died Saturday at a nursing home in the city, municipal officials reported.

Okubo, born Dec. 24, 1897, assumed the title of oldest woman alive in December following the death of a 114-year-old woman in the United States.

According to the Kawasaki Municipal Government, she enjoyed spending time with her son, who lives at the same nursing home. The city did not disclose the cause of death.

Okubo's death leaves Misao Okawa, 114, from the city of Osaka, as the oldest woman, at least in Japan, health ministry officials said, adding that they are trying to confirm her world ranking.

The oldest living person in the world is currently Jiroemon Kimura, a 115-year-old resident of Kyoto Prefecture.