Does my partner have to change her name?

(Context - I’m British my partner is Japanese)

Long story short - my partners (we would be married if not for being separated during the pandemic) mother is getting married to her partner. She is saying that my partner must now change her family name to that of her partner.

I can understand this in principle - she would be added to his Koseki to be able to receive inheritance etc. and would have to change her name.

She doesn’t want to change her name, I don’t want her to change her name. What adds to the confusion is that when we marry she wants to take my family name... So if a note is added to her Koseki that her name is changed then why does she have to change her name? This would mean our children will have an effective strangers name when we have them?

I’m struggling to find any information about this in English and she can’t understand the situation from her research in Japanese. I’m finding it very stressful because I have no idea what is going on and I can’t inform myself properly about any of this. Please.

As far as I know, even when the mother of your partner re-marries and changes her surname (this will happen as she will leave her current “Koseki” and join the guy’s “Koseki”), the kid’s surname does not change automatically (= the kid does not join the guy’s “Koseki” automatically).

Either the guy has to adopt her as his own, or she has to apply to join his Koseki. Neither can be done without the child’s consent. If the child is 15 or older, it is only the child herself who can take this procedure, and the mother cannot force this on her.

About inheritance, as long as it can be established that she is her mother’s child (obvious from her “Koseki”/birth record), that should be no problem.

OK, so she gets to keep her current surname.


The following is just for her thought:
Even after getting married to you, married couples do not have to have “one common surname” if one of the partners is non-Japanese. (Of course if she wants to change to yours, that can be done, though.)

I kept mine (me = Japanese, my husband = continental European). So my marriage to him is in the “remarks” column of my “Koseki,” his surname is stated in (parenthesis) on my passport after my surname so that anyone can see we are married, but my official name remains. He is in my “Juminhyo” (resident record) as the “husband.” No issue whatsoever in terms of official record. Best wishes.

if she (a child ) is not adopted to a new "father", she has no right to inherit his inheritance. adoption means change of family name.
her mother wants to let her child (i.e. OP) get his inheritance.
generally speaking, it may make a new family trouble, if he has his own child(ren).

if she (a child) does not want to have his inheritance, she does not need to change the name.

As mentioned, according to the law, she doesn't have to change her name. But I have a hunch that what her mother is saying is that she has to change her name so that her mother and her partner would feel at ease. And perhaps, her mother believes that it's better for her in the long run. Note, that I'm not saying she should change her name. I'm just answering your question. She should have a good and calm talk with her mom.

"she has to change her name so that her mother and her partner would feel at ease.”
honestly saying, although many liberal people believe that "夫婦別姓" is better, the advise seems to be more traditional. and it is exactly the point at which many conservative people point out that "夫婦同姓" is better for keeping family relationship.

I'd like to remind people that this thread is about mother-and-daughter, not husband-and-wife.

if 夫婦別姓， the child name becomes 親子別姓 "automatically". I think Uco's thought is self-contradictory.
at present, the child can keep the original family name with no legal problem. there is no necessity to support the mother's thought that her child changes the family name to a new one by mother's re-marriage. name change also implies that the child forgets the previous family memory by abandoning the previous name.

ken-san, and to anyone who reads Japanese,

いやいや、そういうことじゃなくて、主さんの彼女さんのお母さんが言っているのは、きっと、「法的に姓を変更する必要があるのよ」ということではなく、「してちょうだいな。しなきゃダメよお」的なことなのかもしれないと思ったんですよね。つまり、お母さんの心情的なものなんじゃないかと。彼女さんとしては、そのお母さんのお気持ちに寄り添って話し合わないと、話が先に進まないのではないかと思ったんです。

ちなみに、彼女さんもそれをわかっていて、主さんに「ねえ、変えなきゃダメなのかなあ。納得いかないわ」と甘えただけなのかも、とも思いました。だとしたら、主さんも心情的に寄り添わないと埒があかないわけで、法律だけを説いても話が進まないだろうと思っただけです。というか、法律的なことなら、役所か弁護士の無料相談を利用すれば済みますよね。

Written above is basically the same thing as what I wrote in my previous English post. The OP's mother is probably more concerned about how surnames may emotionally affect her and her husband-to-be. If so, the OP's girlfriend has to gently approach her mother in order to get what the girlfriend wants.

I also added that, perhaps the OP's girlfriend is not actually asking the OP about lawful facts but rather sort of saying, "I don't want to, Leaf9. Do I have to?" just so that she could feel better talking to her boyfriend. If she really needs lawful facts, she can just use one of those free law consulting services available either at her city hall or through a private law firm.

Just clarifying.