Questions Regarding Koseki, Marriage License, Name Change, and Japanese ID Card (My Number Card)

Hello everyone. I just moved here to Tokyo, Japan with my wife from California.

As you can probably see from the title, I have a good amount of questions.

A little bit about ourselves.

I am 32M, a dual citizen, and fluent in both English and Japanese. Living here, I plan to identify myself as a Japanese citizen.

My wife is 31, a Japanese citizen, has been living in the states since she was about 4 y.o. via green card. Fluent in English. Can speak well in Japanese, but struggles to read and write.

The main thing we would like to know is the order of action we need to take. Additionally, an elaboration on some of the questions will be greatly appreciated.

We have obtained our Koseki, mine from Osaka and my wife’s from Tokyo.

Since we have our koseki, we are planning to get married first. By doing so, this will force us to create our own koseki. Most likely we will be using my wife’s grandmother’s address for the koseki. In this same process, I know it’s not very common, but I am planning to change my last name to my wife’s last name. After completing this, we plan to register for My Number, get our cell phone plans, open up a bank account, etc.

Does this sound like the right or most logical order of events? If I don’t do the name change first and open up many accounts, I feel like everything will get very messy. Also, before I report my income to the US once I start working for Japan, I plan to contact the IRS and let them know that my last name has changed in Japan after my marriage (my last name in the US will be my original). For this purpose would a phone call or email be enough?

Thank you for your time. We appreciate any help!

4 comments
  1. Sounds logical but if you change your name in Japan I would assume it forces you to change your name everywhere including the USA (and for that is a different paperwork I assume)
    In my case, as a foreigner, there was an option in which you can have the Japanese last name of your partner as an additional name that is just valid in Japan (it goes “(—)” like that in your My Number card). however, I don’t know if you have that option. Check in your municipality

  2. Recently went back to Japan to create our own koseki after marrying in the US.

    One of the forms that we had to fill out to create our own koseki had a checkbox about name changes (which party is changing name and what name to use). If the option is available to you, I’d recommend going to the Japanese embassy in the US and asking. They should be well-versed in these types of scenarios, and I’ve never had an issue with just dropping into one.

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