If current laws requiring married couples to share a surname remain unchanged, the entire population of Japan could have the same surname – Sato – by 2531, a study by Tohoku University suggests.
Sato is currently the most common surname in Japan, held by roughly 1.5% of the population.
The research led by Professor Yoshida predicts this number to rise to 100% within the next 500 years.
Yoshida stressed his estimate was “mechanically calculated based on an assumed scenario”, according to Japanese newspaper The Mainichi.
But he added: “If everyone becomes Sato, we may have to be addressed by our first names or by numbers.
The study, commissioned by the Think Name Project and other advocates for surname choice, highlights the potential downsides of Japan’s current legislation.
Unlike most countries, Japan mandates married couples to adopt a single surname, typically the husband’s.
Professor Yoshida’s research indicates a steady rise in the prevalence of the Sato surname. Data suggests a 1.0083% increase from 2022 to 2023. If this trend continues, half the population could be named Sato by 2446, with everyone sharing the name by 2531.
Yoshida said everyone having the same surname “will not only be inconvenient but also undermine individual dignity,” according to Japanese newspaper Asahi Shimbun.
“This would also lead to the loss of family and regional heritage associated with surnames.”
The study also explores an alternative scenario where couples have the freedom to choose separate surnames. In this case, Professor Yoshida predicts only 8% of the population would hold the Sato surname by 2531.
This model takes into account a 2022 survey by the Japanese Trade Union Confederation, where 39.3% of respondents expressed a preference for sharing a surname even if individual options were available.
