Everyone in Japan could have the same surname by 2531 due to marriage laws, claims professor

The number of people called Sato is rising in Japan – but very slowly (PA)
The number of people called Sato is rising in Japan – but very slowly (PA)

Japanese citizens could all have the same family name in about 500 years’ time, suggests a recent study.

As part of a campaign to update the civil code that’s been in place since the late 1800s, the study uncovered that the same family name could be shared by the whole population unless married couples are permitted to use separate surnames. At the moment, Japanese couples must share a single surname.

Led by Hiroshi Yoshida, a professor of economy at Tohoku University, the research identified that every Japanese citizen might go by the surname of Sato-san by the year 2531. The study is based on several assumptions and Yoshida wanted to draw attention to the effect the current system is having on Japanese society.

“If everyone becomes Sato, we may have to be addressed by our first names or by numbers,” the professor said, according to the Japanese publication Mainichi. “I don’t think that would be a good world to live in.”

The growing number of Satos

As it stands, Sato is already the most common surname in Japan, making up 1.5% of the 125.1 million-strong population. The runner-up goes to Suzuki.

While some people thought the study, published on April 1, was a prank, Yoshida wants more people to take the issue seriously.

If all Japanese people shared the same surname, new ways of differentiating between people would need to be found. The professor refers to this as “not only inconvenient but also [undermining] individual dignity”.

As well as posing practical difficulties, losing different surnames would result in a loss of cultural, regional and family heritage.

Between 2022 and 2023, the proportion of Satos increased 1.0083 times. At this rate, around half of the Japanese population would have that name in 2446, reaching 100% in 2531. In Japan 95% of marriages result in the woman changing her name, although that is not specified in the current laws. More and more voices are joining the call for married couple to use separate surnames, something not currently allowed in Japan.

However, although 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.

The main argument comes from conservative members of the ruling Liberal Democratic party, who reason that changing the law would undermine family unity and could cause confusion among children.