I am not an expert on this but hope the below info can assit you to some certain extend...
As you probably know by now that 'Koseki Tohon' is THE master paper to prove who you are and your personal particulars including marital status in Japan. Hence, there is no separate official marriage certificate or divorce certificate exist in Japan. (What the city or ward office does at the end of the day is to update your personal particulars in Koseki Tohon based on your submitted/accepted Kekkon Todoke or Rikon Todoke)
However, in some countries like Singapore, an official paper to prove your marital status is requested. In that case, you can go to the Embassy of Japan in Singapore. They provide service of issuing an official letter in ENGLISH that proves your marriage or divorce status based on your Koseki Tohon.
You can find the details at (only in Japanese language though)
http://www.sg.emb-japan.go.jp/Japanese/ ... ibunshomei
a summary of what you would need is:
- an application form (you can get it from the service counter of the embassy)
- a copy of your Koseki Tohon (issued within the last 3 months by respective ward or city office in Japan)
- your passport
- admin fee: SGD16.00
One thing I am not sure is that a copy of Koseki Tohon your girl friend can get is not her Koseki Tohon but her ex-husband's. Becasue my understanding is that Non-Japanese national (even if you are a PR in Japan) can never have their own Koseki in Japan under the current law.
In that case, I am not sure if the Embassy can issue the above mentioned letter for her to prove that she's been filed for divorcein Japan but I'm sure it worth checking with the embassy.
IF the Embassy of Japan in Singapore cannot help to issue the above mentioned letter for her since she is not a Japanese national, she can perhaps translate what's written in her copy of Koseki Tohon in English first by herself and get a notary public officer to certifiy that all translated details were all correct and accurate. Then, bring the pepers to the embassy of SINGAPORE in Tokyo to get an official letter that certify the papers. This process can be done within 1 day if you are in Tokyo but costs some money as the notary public office charges you around JPY 20,000 or so + the Embassy of Singapore also takes some service charge but not so much.
Wish you all the best!