ANALYSIS | Japanese Marriage Law May Cause Everyone to Have the Surname Sato by 2531

Photo Credit: Real Estate Japan

Unlike many other developed nations, Japan still legally requires married couples to have the same last name. A new study led by Hiroshi Yoshida of Tohoku University projected that because of these restrictive marriage laws, everyone living in Japan might have the surname “Sato” by the year 2531.

Unless Japanese marriage laws are changed, the country continues to face name extinction, where surnames are lost when women become wives and take on new surnames. This is also a result of Japan’s culture of basing their lineage and ancestry off the male line. In Japan, ‘Sato’ is currently the most common last name, with almost two million holders, and this number will only continue to increase. 

Japan’s population growth rate has been consistently declining since around 1973, when the country’s fertility rate dropped below the threshold needed to maintain its population — the base fertility rate is 1.3 births per woman as of 2021. A shrinking and aging population has created a headache for Japanese leaders. A declining marriage rate is undoubtedly one of the main causes.

This diminishing marriage rate could result in the population shrinking more quickly, which would ultimately prevent the last name ‘Sato’ from being taken on by future generations at all. However, if the marriage rate crisis is overcome, Professor Yoshida’s predicted future may come true unless the law is changed.

For Japan, whose country has the fourth largest economy in the world, neither of these futures are ideal. “A nation of Satos will not only be inconvenient but also undermine individual dignity,” Yoshida told The Guardian. “The trend would also lead to the loss of family and regional heritage.” 

Organizations that currently support a change in marriage laws have projected that, by 2351, only 7.96 per cent would have the last name Sato if changes are legislated.

Japan has historically been culturally opposed to couples having separate last names, as it would damage the unity of a family. The law defining this has been in place since 1898 after being adopted during the Meiji Restoration as part of a program of modernization and emulation of Western societies. 

It has since become a traditional element of Japanese culture. Although there is no law saying whether the husband or wife’s last names should be used, 96 per cent of women typically adopt their husband’s names after marriage. If a married couple has different last names, they are not officially recognized.

Across much of Asia, including Japan, last names are less diverse compared to in Western countries. Women’s surnames are lost every generation. Although the Japanese government has allowed women’s maiden names to appear alongside their married names on passports and other certificates, they remain the only country that requires spouses to use the same last name.