Changing my surname in Japan

I will be marrying my fiancé soon, he is Japanese and I hope to take his surname. We both live in Japan but I am British.
I have tried reading the process of changing my Surname in Japan but I have not found much luck.
Can anyone shed any light on the process?

Congratulations on your engagement!

As you are British, the British authorities are the only ones who can do anything about officially having your surname changed. So please ask the relevant authorities of your country (after youfve reported the marriage to the UK authorities).

Our situation was the opposite – I am Japanese, my spouse European, we got married in the UK, and our British marriage certificate says gbride keeps her maiden nameh (because the authorities in the UK couldnft do anything about my name,) we came back to Japan some time later, where we reported the UK marriage to the Japanese authorities. Ifve decided to keep my maiden name though, after all. (gSame surnameh rule does not apply to marriages other than Japanese-to-Japanese.)

hi
im british too, got married in Japan and changed my surname to my husbands japanese ones.

at first, straight after marriage i was put into my husbands koseki with my maiden name, as mentioned before japan doesnt have authority to change your name.

as im sure youre aware in the UK the rules around name changes are very loose, you can do what you want really. its providing some form of proof that your local city hall in japan would be happy to take that can be a challenge, due to the name change procezs being a lot stricter.

all i did is returned to the UK and changed my name on any government ID, passport etc.
then i went to a solicitors who have a Notorial service who can affirm documents. i had them write up a document of me affirming i have changed my name under UK law and they done their ribbon and official stamps etc .

i then got my husband to write a translation and stamp his hanko on it.

we then took it to city hall in japan and asked to change my name on my husbands koseki.
i have heard of people not changing the koseki name and not ever having a problem, this is up to you whether you go ahead with this.

when i entered japan on my spousal visa my name was entered as per my passport on my resident card (as i already changed my name it was no problem)
so when i went to city hall to register my address the resident record they used my resident card name.

do you already live in japan and have resident card in your maiden name?
if so change your name under UK law (ie change your passport etc) and report it to immigration and see what they say, they should be able to give you a new card and you can take it to city hall to change your residents info there. but i havent done this myself so dont know the process, as i mentioned i entered with my visa done in my new name.