TOKYO (BLOOMBERG) - Japan's rapidly ageing society will see a quarter of its breadwinners turn 75 or older by 2040, the Nikkei reported, citing a study from the National Institute of Population and Social Security Research.

The total number of head-of-households who are 75 years of age or more will mount to 12.17 million by that year, while the number of single-person households will climb to 19.94 million, or two-fifths of the total, the report said.

The number of people living alone who are 75 or older will top five million, it said.

As the number of elderly Japanese people living by themselves increase, the country is increasingly in need of a revamp of its social security system and relevant infrastructure, the report said.

Japan's government has been opening the door to more low-skilled foreign workers as the rapidly ageing population fuels a labour shortage.

With unemployment at just 2.3 per cent, near the lowest since the early 1990s, labour shortages are being felt in a range of industries from convenience stores to construction before the Tokyo Olympics next year.