Yes UK citizen with PR due to Japanese wife - got it pretty quickly actually think I impressed Immigration by self preparing my app without any help from the Mrs.

Japan and the UK don't have a pension totalisation agreement so they're separated.

The UK government will quite happily continue to take Pension contributions from me whilst overseas known as National Insurance to build up Contribution Years towards the 35 you need to get a full state pension.

It's actually been rather cheap up until now - if you have 2 years I think of contributing full rate contributions via UK based contributions you were allowed to overseas to pay at a rate of $220USD a year to build up a valid contribution year for pension after going overseas known as "Class 2 National Insurance". However unfortunately the government is scrapping this from next year at which point I'll have to start paying Class 3 contributions which will see weekly rate go up to £13.40 from £2.40.

However that notwithstanding....

Current Japanese Pension - 66,000 yen = £488 a month

New UK state pensio - £159 ish a week = £636 a month

Currently the Basic State Pension contribution is :-

UK - £13.40 - rising to £40 - 50 a month from next year.
Japan - £120 a month

I am paying LESS to the British government for my state pension and when I reach pension age I will get MORE in pension payments. Not to mention there is no guarantee that the level of payment in the Japanese system can be maintained - I seriously suspect the amount will FALL to keep the system liquid.

HENCE you can probably see my reluctance at being forced to pay pension to Japan based on these circumstances but unfortunately I have to because the law says I do. I have no qualms in paying my wifes state pension as she's already got over 20 years contributions built up but for me starting from scratch in my 30's it seems quite a bad investment....