The number of Japanese living beyond 100 has almost quadrupled in the past 10 years, with the once-exclusive centenarian club expected to surpass 28,000 this year, the government said Friday.

The Health Ministry said Japan was likely to have 28,395 citizens aged 100 years or older at the end of September, a jump from last year's record 25,554 — of which women comprised 85 percent. The ministry conducted a nationwide survey and the figure is a projection of centenarians by the end of the month.

The number of people living older than 100 has been on the rise since 1971, and has accelerated since 1996 when Japan had 7,373 people who had reached three figures, according to the ministry.

The rapid increase underscores both positive and negative sides of the country's aging population.

While experts say that there are more active centenarians than before, the rapidly graying population adds to concerns over Japan's overburdened public pension system.

Its centenarian population is expected to reach nearly 1 million — the world's largest — by 2050, according to U.N. projections.

Yone Minagawa is the oldest woman at 113 in the southern Japanese prefecture of Fukuoka, while the oldest man at 110 is Tomoji Tanabe in another southern prefecture, Miyazaki, the ministry said.

Tanabe drinks milk and keeps a diary every day, saying that the key to long life is not to drink alcohol, the ministry said.

Tokyo has the most centenarians with 2,562. Okinawa, Japan's southernmost chain of islands, has the highest concentration, with 740 centenarians, or 54 for every 100,000 people, well above a nationwide average of 22 per 100,000.

The ratio for the United States is about 10 in 100,000.

The announcement was made prior to Respect for the Aged Day on Sept. 18, a national holiday honoring the country's elderly, when the government gives each new centenarian a letter from the prime minister and a silver cup.