This footage was filmed and produced 15 February 2024.

In Japan, everyone could one day have the same surname unless restrictive marriage laws change, according to a new study. But the country's dwindling marriage rate could halt that trend, and a rapidly declining population could make it completely obsolete.

Unlike most of the world's major economies, which have done away with the tradition, Japan still legally requires married couples to share the same surname. Normally, wives take the husband's surname, and same-sex marriages are still not legal in Japan.

Now a movement is brewing to change the surname rules, led by women's rights advocates and those seeking to preserve the diversity of Japanese surnames in a nation where a handful of names are increasingly common.

If the rules hold, all Japanese could have the surname Sato by the year 2531, according to Hiroshi Yoshida, an economist at Tohoku University in Sendai, who led the study.

According to Myoji Yurai, a company that tracks Japan's more than 300,000 surnames, Sato is currently the most common, followed by Suzuki. Takahashi is in third place. About 1.8 million of Japan's 125 million people have the surname Sato, Myoji Yurai says on its website.
Yoshida - whose surname is the 11th most common - was commissioned by the Think Name Project, a group calling for legal changes to allow couples to keep both their surnames.

The professor, who released his latest study on Monday, admitted that his projection would only hold up if the country could overcome what is already one of its most pressing crises: a declining marriage rate.
The number of marriages in Japan fell nearly six per cent in 2023 from the previous year to below 500,000 for the first time in 90 years, while divorces rose 2.6 per cent last year, according to official figures.

This footage illustrates various of Tokyo's streets.