TOKYO: Six days a week, winter or summer, 73-year-old Mitsumi Kobuna gets up at 5am to go to Tsukiji fish market to stock up his family-run stall.

He will be at work for around 15 hours, in a job he has done for 55 years.

He has noticed his body slowing in the last decade or so, but would really like to carry on for two or three more years.

While governments in Europe have struggled to convince their populations to delay retirement, Japan has found no such resistance, and people like Kobuna are not unusual.

Men in Japan work until they are 69 on average, five years longer than the developed countries club of the OECD and a full decade longer than their counterparts in France.

Japanese women retire at a mean age of 67 against an OECD average of 63.

Observers say people prepared to work longer and later in life are increasingly necessary in Japan, where a shrinking number of taxpayers find themselves supporting a population of elderly that is both growing and living longer.

Around a quarter of Japan's people are over 65, a figure that the government estimates, will rise to 40 per cent within half a century.

Without the immigrant workforce that many developed countries have, getting people to stay at work is seen by many as one of Japan's only options if it is to pay for its own population.

But for many of those in the autumn of their lives, their jobs are not merely a chore to be endured, but rather a source of pride, and something that gives them energy.

“If I stopped work, I would feel old,” said Koji Sato, who runs a tea shop in Tokyo. At 75-years-old, Sato says he works 12 hours a day and frequently seven days a week. “I've been doing this for 50 years,” he said. “I'm slowing down gradually, but the day I stop that will be the end of me.”

This attitude is common in many Japanese who grew up in the austerity of the post-war years, when a devastated shell of a country was transformed by the sheer effort of its people into a booming, world-beating economy in less than two decades.

For Kenji Wada, a 73-year-old lawyer who specialises in industrial patents, his job is about so much more than the pay he brings home.

“Money is secondary,” he said. “The key is to be doing something useful in society.” He said that in the 40 years he has been running his practice he has worked for many different companies.

“They entrust me to handle things, no matter how old I am.” Shigeru Oki, director of the Business Policy forum, a government-backed think-tank, said working longer was a way to feel useful.

Some seniors cite economic reasons but it's not the only reason. According to our surveys, they often said they wanted to have something to live for, remain connected to society and maintain health.

In August and without much fanfare, the government passed a law that comes into effect in stages requiring companies to let their employees continue working until they are 65.

They also raised the age at which pension payments begin, to 65, by 2025.

People are allowed to continue working beyond that age, provided their employer is willing to employ them.

“Seniors know that the pension system has become a burden on younger generations due to the decline in childbirths,” said Oki.

“They feel they can accept delays in pension payments up to the age of 65 or so in the face of the country's bad financial situation. Besides, people in their 60s are (today) much more vibrant than those in the past.”

Months of protests greeted then-president Nicolas Sarkozy when he increased France's age of retirement progressively to 62 from 60 in 2010.

Moves in Greece to hike to 67 the age at which people can retire have been part of a wildly unpopular austerity package that has seem sometimes-violent street protests and a series of strikes.

The outcry in Europe stands in marked contrast to Japan, where there was barely a murmur. Work is just something one does, and does not complain about it.

“I've never really considered if my work is fun or not,” said Seichiro Fukui, who for 41 of his 64 years has worked as an insurance broker, an estate agent and a vendor of rice cakes.

“My father toiled until he was 80 years old and I intend to work until I drop. My life is built like that and it's not going to change now.” And here, for many ageing Japanese is the nub of the problem: in a society built so firmly around work, where is meaning to be found in retirement?

For Fukui, the answer is to carry on. “I don't know what I would do with myself if I retired.”