Photo/IllutrationAn elderly woman lives alone in this housing complex in Chiba city designed for senior citizens. (Asahi Shimbun file photo)

Japan's population is not just rapidly aging, it is also becoming a lonelier place for elderly people.

A projection released April 19 by the National Institute of Population and Social Security Research found that close to 9 million senior citizens aged 65 or older will be living alone in 2040.

The forecast of household numbers is made once every five years. The projections for 2040 were based on census data from 2015.

The study found that 8.963 million senior citizens will be living by themselves in 2040. The figure represents a 43.4 percent increase over 2015 and means that 17.7 percent of all Japanese households in 2040 would be composed of isolated senior citizens.

Living alone will also extend across age groups as the study found that 39.3 percent of all households would have a single member in 2040.

The problem of isolated senior citizens just 21 years down the road will be especially dire for Tokyo as 1.167 million residents will likely be living alone.

Experts called for urgent measures to deal with the growing need for elderly care and other services as those senior citizens increasingly become unable to care for themselves.

"There will be even greater need for elderly care services and neighborhood watch programs to check on such senior citizens," said Shiro Koike, director of the institute's Department of Population Structure Research, referring to the increase in elderly people living alone. "There is a need to think about support measures in order to prevent seniors from becoming isolated in society."

Given the current shortage of those providing elderly care services, the central and local government budgets will surely come under greater strain as the problem of single older people makes itself felt.

The study found that in 2040 there would be 50.757 million households in Japan, down 4.8 percent from 2015.

Couples living with their children would make up 23.3 percent of all households, while couples would make up 21.1 percent. A single parent living with a child would constitute 9.7 percent of all households, with 6.6 percent of households living under other arrangements.

By 2040, households headed by a senior citizen would represent 44.2 percent of the total.

In 10 prefectures, more than half of all households would be headed by a senior citizen in 2040.