Everyone in Japan might end up having this popular surname by 2531, new study reveals

Imagine a world where everyone has the same surname. Well, not maybe the entire world, but Japan is not far from achieving that feat. It is believed that by 2531, every individual in Japan will end up having the same surname, per the research and simulation run by Tohoku University. Ninety-six percent of people decide to take the man's surname when they get married following the law (keep in mind that same-sex marriage is still not legal in Japan). 

Professor Hiroshi Yoshida from Tohoku University's Research Center for Aging Economy and Society stated that the law of taking up either the man or woman's surname after marriage needs to be changed and if it's not done, there will be a situation where every family in Japan will have "Sato" as their surname. Sato started to become a popular surname in Japan in 2023, and now about 1.529 percent of the Japanese population use it, per IFL Science.

The number might seem low, but between 2022 to 2023, the surname grew in popularity by 1.0083 times, and it continues to become even more popular as time goes on. At that rate, there's a good chance that in a few year's time you could be standing in a crowd full of people in Tokyo and shout "Sato," and every other citizen will look in your direction by 2531.  "From a general probability perspective, there are many cases of people marrying into a group with a major surname," the university's research paper explains. "And if this process is repeated over a long period, there is a possibility that they will be absorbed into the Sato surname and converge."

But folks might escape the wave of Sato's—or at least mitigate it—if the country makes certain changes to their surname adoption law to allow women to keep their orginial surnames after marriage. The research states that if this law is brought into effect, by 2531 only 7.96% of Japanese citizens will end up with the surname Sato (assuming that 39.3% choose to continue to select one surname, which is equal to the amount of people who said they would do so in the 2022 survey).

If no changes are made, however, then Japan is looking towards a "Sato totality" by 3310. According to 'Japan's Future Population Projections' 2023.4, "the Japanese population in 2120 is estimated to be 41,229,000. If this pace continues, the Japanese population is estimated to be 281,866 in 2,531 and 22 in 3310…In other words, even if 100 percent adoption of the Sato surname is postponed for 800 years, there is a high possibility that the Japanese people themselves will become extinct before that due to the declining birthrate."

According to The Guardian, Yoshida's research was commissioned by the Think Name Project and other organizations that want to legalize the opportunity to select your surname, per the reports of Mainichi Shimbun. Those advocating for a change in the rule regarding married surnames anticipate that the possibility of Suzuki, Watanabe and even those with the 11th most common surname, Yoshida might disappear one day.

Although Japanese folks are allowed to have married and maiden names placed next to one another on their passports, driver's licenses and residency certificates, the country happens to be the only nation in the world that mandates couples to use the same surname. According to conservative members of the ruling Liberal Democratic Party (LDP), bringing changes to the preexisting law would "undermine" family unity and end up confusing youngsters.