Japanese citizens will all have the same family name in 500 years’ time unless married couples are permitted to use separate surnames, a new study has suggested as part of a campaign to update a civil code dating back to the late 1800s.
The study, led by Hiroshi Yoshida, a professor of economy at Tohoku University, projected that if Japan continues to insist that couples select a single surname, every single Japanese person will be known as “Sato-san” by 2531.
Yoshida conceded that his projections were based on several assumptions, but said the idea was to use numbers to explain the present system’s potential effects on Japanese society to draw attention to the issue.
“If everyone becomes Sato, we may have to be addressed by our first names or by numbers,” he said, according to the Mainichi. “I don’t think that would be a good world to live in.”
Sato already tops the list of Japanese surnames, accounting for 1.5% of the total population, according to a March 2023 survey, with Suzuki a close second.
Some social media users wrongly assumed the study, first reported on Monday but published in March, was an April fools’ day prank, but Yoshida said he wanted it to give people pause for thought.
A nation of Satos “will not only be inconvenient but also undermine individual dignity,” he said, according to the Asahi Shimbun, adding that the trend would also lead to the loss of family and regional heritage.
According to Yoshida’s calculations, the proportion of Japanese named Sato increased 1.0083 times from 2022 to 2023. Assuming the rate remains constant and there is no change to the law on surnames, around half of the Japanese population will have that name in 2446, rising to 100% in 2531.
Couples in Japan have to choose which surname to share when they marry, but in 95% of cases, it is the woman who changes her name.
However, the picture would be different if Japan’s government submitted to growing pressure to allow married couples to use separate surnames.
The study contained an alternative scenario extrapolated from a 2022 survey by the Japanese Trade Union Confederation, in which 39.3% of 1,000 employees aged 20 to 59 said they wanted to share a surname even if they had the option of using separate ones.
Under those circumstances, Yoshida, whose study was was commissioned by the Think Name Project and other organisations that want to legalise the opportunity to select your surname, projected that by 2531, only 7.96% of the Japanese population would be named Sato, the Mainichi Shimbun reported.
Groups calling for a change in the law on married surnames hope their campaign will receive a boost from the prospect that Suzukis, Watanabes and, indeed, people called Yoshida – the 11th most common surname – could one day disappear.
While the government has allowed maiden names to appear alongside married names on passports, driving licences and residence certificates, Japan remains the only country in the world that requires spouses to use the same name.
Conservative members of the ruling Liberal Democratic party (LDP) say changing the law would “undermine” family unity and cause confusion among children.