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Why All the Married People in Japan May End up with the Same Last Name

Due to a law passed over 100 years ago and population demographics, all the married people in Japan may end up having the same last name. If you grew up having a popular name in your class (think of “Jennifer,” “Cameron,” or “Taylor”), then you know the frustration of being called on by your teacher and not being the Cameron she/he wanted to address. Imagine everyone on your block having that problem! Read on to find out more!

Japanese geisha with red parasol

Hey, Christie!

My fiancé, Sam, was kidding around the other night about whether I should take his last name after we marry or hyphenate our names or keep my maiden name. I am currently Sarah Hardy. If I take his last name, I become Sarah Harr. If I hyphenate our last names, I become Sarah Hardy-Harr. I know, right? As we discussed this, he casually mentioned that all the married people in Japan would all have the same last name one day. Is this true???

–Sarah the Surprised in Salem, Oregon


Hey, Sarah!

Sam is right: According to Professor Hiroshi Yoshida of Tohoku University, in about 500 years, all married people will have the same last name of “Sato.”


This is because of an antiquated law dating back to the late 1800s which requires any married couple to share the same last name. Most of the time, his last name is the one chosen. (Japan might be the only nation which requires this.)

While “Smith,” “Jones,” “Garcia,” and “Brown” are common last names in the U.S., the two most common last names in Japan are “Sato” and “Suzuki.”

(Fun fact: In the second Karate Kid movie, Mr. Miyagi’s nemesis carries the last name of “Sato.”)

How did Professor Yoshida arrive at the conclusion that there would be a Sato tsunami in the coming years? The number of people with the last name of “Sato” increased from 2022 to 2023. If the rate of increase continues at that pace AND that antiquated law isn’t changed, then 50% of the Japanese population will have the last name of “Sato” by 2446. 



Japanese traditional bride and groom
young Japanese couple

That could increase to 100% of married people by 2531 all having the last name of “Sato.”

Could change be coming to Japan? Yes. According to a 2022 survey, only 39% of single people from ages 20 to 59 were interested in sharing their spouse’s last name after they marry. This may nudge the lawmakers to change the law.

If you have any additional questions, please reach out to me.


Your friend in the wedding business,

Christie Shyne


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