Claiming Japanese pension after leaving Japan.

I’ve been paying pension for 11 years in Japan and I recently divorced from my (Japanese) wife and I’ve just moved back to the UK.

I can claim a chunk of my Japanese pension from the UK but my wife can’t claim her share unless I send a document similar to a ‘Koseki’ but we don’t have that here in the UK and similar documents don’t exist. I phone around for advice but I could t get any help, I also contacted the UK pension office to get a ‘life certificate’ but I can’t apply for one unless I’m already retired and wanting to claim my UK pension.

Anybody have any experience of this before or have any advice on what documentation could be useful?

Thanks for reading!

https://www.reddit.com/r/japan/comments/13jhy71/claiming_japanese_pension_after_leaving_japan/