TOKYO — The number of senior citizens living alone in Japan will likely jump 47 percent by 2050, a government-affiliated research institute said on Friday, underscoring the heavy burden the country's demographic change will exert on its social security system.

The number of single-person households is expected to reach 23.3 million in 2050, accounting for 44.3 percent of total households. That would be higher than 38 percent in 2020, the National Institute of Population and Social Security Research said.

Of those one-person households, senior citizens aged 65 or older will likely represent 46.5 percent in 2050, compared with 34.9 percent in 2020, the institute's estimates showed.

Japan, one of the world's most advanced ageing societies, has seen a constant decline in the number of marriages in recent decades as a stagnant economy hits the young generations the hardest. The COVID-19 pandemic also came in the way of people meeting their potential partners and tying the knot.

Nearly one-third of Tokyo men in their 50s have never been married, while data gathered by Recruit Holdings shows 46 percent of men and 30 percent of women in their 20s in Japan have never dated.