Simulation reveals all Japanese will have the same surname by 2531

Konnichiwa, Sato-San

A simulation run by a Japanese professor and released on Monday revealed that by the year 2531, everyone in Japan will have the surname Sato.

Not that there's anything wrong with the name Sato, of course. It's currently the most popular surname in Japan with more than 1.5 percent of the population proud to call it their own – slightly ahead of Suzuki.

There are, however, comparatively few surnames in Japan for the size of its population. It's estimated that the ten most popular Japanese surnames cover 10 percent of residents.

Professor Hiroshi Yoshida, from Tohoku University's Research Center for Aged Economy and Society, used data available on the internet – gathered from government statistics and phone books – and determined that Sato increased its prevalence 1.0083 times between 2022 and 2023.

He then assumed a constant growth rate – a big assumption, but he was trying to make a point – to calculate how quickly it would take for the most popular surname to spread to the entire population. He also incorporated projections about the country's population growth.

Yoshida found that by 2446, over half of the population would be called Sato. And by 2531, everyone would bear the name.

The exercise was designed to encourage change to Japan's civil code, which requires married couples to have the same surname.

Should Japan rethink its policy, less than eight percent of the population is projected to be surnamed Sato by 2531. However, the name would still eventually become ubiquitous – it would just not happen until the year 3310.

To reach that conclusion, Yoshida assumed 39.3 percent of the population would share a last name once married – in accordance with a figure calculated by a 2022 Japanese Trade Union Confederation survey of single people who wished to share a surname.

However, the boffin pointed out that the year 3310 prediction was irrelevant – by that year the Japanese population would include only 22 people thanks to its population decline. By 2531, the Japanese population was projected at 281,866.

"In other words, even if 100 percent of the Sato surname is postponed for 800 years, there is a high possibility that the Japan itself will be destroyed due to the declining birthrate before that," wrote the professor (via machine translation).

"These estimates are preliminary estimates based on a number of hypothetical scenarios and do not represent a definite future," he disclaimed, fairly obviously.

The study [PDF] was released by the Think Name Project – an organization that advocates letting couples decide whether to join names or not.

"This project encourages people to think about the diversity of names," declares the Think Name Project website.

"Japan is the only country in the world where married couples must have the same surname," it claims. And while couples can choose either name when they wed, the statistics are skewed heavily toward men keeping their names, with some 95 percent of women taking their husband's name.

More immediate concerns

While paucity of surnames is a long-term concern for Japan, the nation's more immediate worry is whether this week's imposition of overtime restrictions hurts its economy.

Thanks in part to its declining population and aging workforce, the country is experiencing an acute labor shortage – but also an epidemic of overwork. Japan therefore decided to cap overtime hours for drivers of trucks, taxis and buses to roughly 18 hours per week, or 960 hours a year.

The reduction in hours worked is expected to reduce delivery capacity in Japan by 14 percent. Price increases are also anticipated.

Doctors and construction workers – as well as other industries and roles – also have seen their overtime hours capped in what is known as the "2024 problem."

To compensate for a lack of taxi drivers, Japan will partially lift a ban on non-taxi ride-sharing services. ®

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