In 500 years, all Japanese will have the same surname if the country’s marriage laws don’t change

In the year 2531, all Japanese people will have the surname Sato, a study shows. And that is because of the current marriage laws, which many believe are outdated.

It is Professor Hiroshi Yoshida who sounded the alarm. He is an economics professor at Tohoku University and is concerned about his country’s shrinking population. To draw attention to this, he conducted research into Japanese surnames, among other things. According to his study, all Japanese would bear the surname Sato by 2531.

This is due to the marriage laws in the country. Couples in Japan must choose which surname they will use from the moment they are married. The man’s or the woman’s. Japan is the only country in the world that requires married couples to use the same name and in 95 percent of cases it is the man’s.

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Sato is currently at the top of the list of the most common surnames. About 1.5 percent of the Japanese population bears the name. That may not seem like much, but according to Yoshida’s calculations, the share of Japanese people named Sato increased by 0.83 percent between 2022 and 2023. Assuming this percentage remains constant and there is no change in the law on surnames, about half of Japan’s population will have that name in 2446. By 2531 it will be the entire population.

“If everyone becomes Sato, we may have to be addressed by our first names or by numbers,” he said, according to the newspaper Mainichi. “I don’t think this is a good world to live in.”

Adjustments

The research was commissioned by the Think Name Project and other organizations that want Japan’s marriage laws to change so that couples can choose to have different surnames. Under that scenario, Sato’s share would reach just 8 percent of the population by 2531, Yoshida says.

A survey was already conducted by the Japanese Trade Union Confederation in 2022. At that time, only 39.3 percent of those surveyed indicated that they would still choose the same surname even if they had the option to keep their own surname.

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