If you are paying Basic National Pension Contributions, they will stop collecting Contributions at age 60.
The Pension will be calculated based on Number of Months of Contributions to Age 60 for the Basic National Pension, payable at 100% of the benefit based on those contributions, Not on the Full Basic Pension.
If at age 60 you have contributed say 25 years (300 months) then at 65 you will receive Basic Pension of 100% of that 300/480 of the Full Basic National Pension.
If you are contributing to the Basic National Pension, then it would be a good idea to continue paying Voluntary Basic National Pension Contributions to age 65, so you get an additional 5 years' (60 months') Contributions to bring your pension at 65 up to 100% of say 360/480 of the Full Basic National Pension. You have to visit the local Pension Office to apply to make Voluntary Contributions, and you can do so from the day before your 60th. birthday.
https://www.nenkin.go.jp/international/ ... nsion.html
See the Benefits Section and the Voluntary Contributions Section.
If you are in employment, then you and your employer will be paying into one of the employment Pension Systems
https://www.nenkin.go.jp/international/ ... loyee.html
https://www.pmac.shigaku.go.jp/en/index.html
or other...
You will keep paying Contributions as long as you are working up to age 70, and benefits will be calculated accordingly.
Whenever you start receiving the pension, it will be based on Contributions to that date at the rate receivable at age 65, and either discounted if under 65 (100% - % shown)
https://www.nenkin.go.jp/service/jukyu/ ... 21-01.html
or increased if over 65 (100% + % shown)
https://www.nenkin.go.jp/service/jukyu/ ... 21-02.html
Some people (a guest on the Rational Reminder Podcast with Ben Felix) did some calculations (in Canada) concerning whether it was more beneficial to take the Pension at 65 or to postpone taking the Pension to a later date. I can look up the reference. I have quoted it before.
Their conclusion, based on the way the Benefit Increases are calculated based on Inflation and the Markup, was that it would be better to take the Pension at age 65, and not postpone. They calculated that the Pension Office increases the amount receivable in line with inflation, but you reduce the amount you will receive as you have less years to receive it...
Pension Income is taxable in Japan, both National and Residents' Income Taxes, and assessed for National Health Insurance Premiums, but it is eligible for the big Public Pension Tax Deduction in addition to standard allowances and deductions (along with National Pensions from other countries; UK State Pension, Aus SuperAnnuation, Canadian RSS, US Social Security, and so on... which are only taxable in Japan, unless you are receiving US Social Security as a US Citizen, in which case it is also taxable in the US).
If you need the money at 65, you can take the Pension and spend it.
If you don't need the money at 65, you can take the Pension at 65 and feed it post-tax and NHI directly into a NISA, after which future gains will be completely Tax Free, and probably better than the increase the Pension System will give you for postponing.