Everyone in Japan will be called Sato by the year 2531 because of the country’s marriage laws

In 500 years, everyone in Japan will have the last name Sato thanks to the country’s current marriage laws.

If the practice of requiring married couples to share the same surname – rather than retaining their birth names – continues in Japan, there may not be any other surnames left by the year 2531.

Japan is the only country in the world that requires spouses to use the same surname, following an archaic civil code from 1898.

In 2023, the most common surname in Japan was Sato, accounting for about 1.5 percent of the country’s population.

An economics professor at Tohoku University, Hiroshi Yoshida, has predicted that if this continues, the only surname left will be Sato, which will inevitably lead to social chaos.

In the scenario, all sports teams, classrooms, and offices would be referred to as Sato-san.

But this result would be a product of Japanese marriage laws that establish that Japanese people who marry must adopt the surname of one or the other of them.

In 95 percent of cases, this means that women give up their maiden name and take their husband’s surname.

In Japan, about 500,000 new marriages are registered each year, which means that almost half a million people lose their surname each year.

Sato’s annual growth rate is reportedly increasing by 1.0083 percent based on the date collected between 2022 and 2023.

In Japan, more than 5% of the country’s population shares only four surnames: Sato, Suzuki, Takahashi and Tanaka.

If no changes are made to the current legislation, the hypothesis suggests that 50 percent of surnames will be Sato in 2246.

A series of legal challenges have failed to overturn the marriage laws seen in Japan today, even after several complaints have been filed highlighting that they harm women who have built their careers under their maiden name.

However, until Yoshida’s study, no one had fully recognized Sato’s seemingly unstoppable rise and the consequences his acquisition could have on society.

Yoshida told Japanese newspaper The Mainichi: “If everyone becomes Sato, we may have to address ourselves by name or by numbers.”

“I don’t think that’s a good world to live in.”

A country full of Satos “will not only be inconvenient but will also undermine individual dignity,” he said in an interview with the Japanese newspaper Asahi Shimbun.

“This would also cause the loss of family and regional heritage associated with surnames.”

The study, which uses data from the Japan Trade Union and Trade Confederation in 2022, also revealed that allowing different surnames would push back the chance of a dominant name to 7.96% by 2531.

But they suggest that, due to the declining birth rate, the Japanese population is predicted to be extinct by then.

The study was supported by the Think Name Project, a group that advocates for a change in the selective system of separate surnames.

Groups calling for a change to the law on married surnames hope their campaign will get a boost from the possibility that names like Suzuki and Yoshida, the 11th most common surname, may one day disappear.

Yoshida’s study was reported on Monday and many assumed it was an April Fool’s Day prank, but the professor said he wanted to make people stop and think about the shocking, but very possible, scenario.