Japanese alias name (通称名, tsūshōmei)

Japan allows foreigners to register a legal alias (通称名, tsūshōmei) and use it as their name in some situations. In this post I’ll describe why and how I did this, and what it changed for my everyday life.

My reason

So why did I decide to register a Japanese alias? It’s all about family.

In Japan each family is registered in the family registry (戸籍, koseki), with everyone in the family having the same surname. The family is defined as parents and children, so when a person gets married they move from their parents’ koseki to their newly created one. This means that spouses must have the same family name after marriage (they get to choose one, usually the husband’s), and their kids will all have the same surname as well (until the kids get married or if the parents divorce). However the family registry only has entries for Japanese people (citizens), not for foreigners, so if a Japanese gets married with a foreigner they can both keep their old names.

When we got married, my wife (who is Japanese) moved from her parents’ koseki to her newly created one, and I got added as a note saying that the husband is a foreigner. At this point we had a few options for my wife’s and future kids’ family name:

  1. My wife changes her surname to mine in katakana, so サボー. Then the kids would have the same surname.
  2. My wife keeps her surname (木村, Kimura) and the kids get her surname.
  3. My wife keeps her surname and after our kids are born we apply to the family court to allow the kids to move to their own koseki and get my name

Both of our family names are among the most common names in our countries, so neither of us is very attached to it. Thus the decision came down to convenience: as we intend to stay in Japan long term, our kids are better off with a Japanese family name. (I always have to repeat my name multiple times when making restaurant reservation, while my wife just says Kimura and everyone knows even the kanjis.) So my wife and our recently born baby are both 木村.

However this might present a problem for me: as all Japanese families share the same family name, some people might expect the same from us. I’m a bit worried that if I go to a hospital, school or on a trip with our kid(s), it might be an issue that we don’t share a name, and there is no easy way to prove our relationship.

To further reinforce this, when we went to the hospital for the delivery, sometimes the staff asked me to leave the room and wait in the lobby. When they wanted to call me back, they called me Kimura san (since they never asked my name, they simply used my wife’s surname which works for Japanese couples).

So how can I become sort of Kimura? I could change my name in Hungary and become legally Kimura, then update all of my documents here (which would make me Kimura and not 木村, as they would use my name as it’s written in my passport), but that feels like too big of a change (also my Japanese is very far from being native, so I feel like having a very Japanese name and using it at work, bank, hospital, etc. would lead to confusion). And that’s how I decided to register 木村 as my legal alias, which means I get to have both names and decide which one I want to use in each situation.

The process

Alias registration is done by the city one lives in. It seems like it’s not fully regulated centrally, and cities get to make up some of the rules on what they accept as a reason for doing it. I live in Mitaka, so I went to the Mitaka city hall. First they told me that the purpose of the alias is to register a name that one has been using for a while, so they asked me if that’s the case. (If I say yes, then based on online sources they likely would have asked me for proof of this, e.g. utility bills, shipping labels, business card, etc.) I said no, and explained that the reason is to have the same family name as my wife and kids. The person at the counter then went to the back to check, and came back saying that this was a good enough reason. I filled out a form, and that was it.(The form had a field for the reason and the city hall staff recommended simply writing that I want the same family name as my wife.)

They wrote my alias on my MyNumber card as 通称: 木村マーク at the place where they write your new address after moving. At next renewal it is supposed to go to the top of the card next to my real name like SZABO MARK (木村マーク).

After the city hall, I printed a 住民票 (jūminhyō) at a konbini and this has 通称 as a separate field on the right of my normal name.

Then I went to the police station to update my driving license. They gave me the standard form for address or name change, and I was told to write it as a new name like this: SZABO MARK (木村マーク). They wrote this in full at the section where address changes go, and told me that this will go to the top of the card on next renewal.


Actually there is no next steps for me on this. I could tell my company about it and ask them to change my name to 木村マーク but I’d rather keep my current name for now. I might start using it for everyday things related to my family (e.g. ordering things online, maybe hotel reservations for family trip). But what’s important is that now I have multiple government issued IDs that have the same family name as the rest of my family.

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