but did google and find this, which might be of interest to you and anyone else reading this thread:
Tokyo Pension SystemLike the medical treatment insurance system, Japan also has a pension system. Every citizen must enroll in the pension system.
In the case of old age, disability or death, the purpose of the system is to ensure stable livelihood by providing benefits.
National Pension PlanThe National Pension Plan covers all people between the ages of 20 and 60 living in Japan (including students) and provides equal basic pension benefits. Foreigners living in Japan must also subscribe to this plan.
Enrollment ProceduresAt the National Pension Section of your local ward, city, town or village office.
Premiums
- ¥13,580/month (To be revised every year)
When the income for the previous year is below a certain level, an application may be made for exemption of this premium payment (full or half of the amount). For students who are under the age of thirty with an income below a certain level, an application may be made to defer premium payments.
- Additional premiums ¥400/month
If desired, payment of this additional premium will qualify the payee to receive an additional pension to the Basic Pension for the Elderly.
*The National Pension Fund Plan is also available as a top-up to the Basic Pension for the Elderly.
Pension PaymentsThe National Pension Plan includes the Pension for the Elderly, Pension for the Disabled and Pension for the Bereaved. In order to receive the abovementioned pension, subscribers are obliged to have paid the designated premiums. As the Pension for the Elderly requires subscribers to have paid premiums for 25 years or more, foreigners who began living in Japan in their middle- or old-age may not be able to fulfill the prescribed pension enrollment period. For this reason, measures have been adopted for foreigners who have been naturalized or granted permanent residence, to allow them to count the period spent outside Japan for pension payments.
Pensions can be transferred to overseas financial institutions so they can be received outside of Japan.
Lump-sum Reimbursement for Short-Term Foreign Residents Who Withdraw from the Pension Plan
For foreigners paying the National Pension Plan premiums as Category One Subscribers, when the period for which premiums have been paid and one-half of the period that payment of one-half of the premium value has been exempted total at least six months, and no pension has been received, a lump-sum reimbursement will be made if upon returning to their home country a claim is filed within two years of the date of leaving Japan.
Lump-sum WithdrawalsDetermined as between ¥40,740 and ¥244,440 (in fiscal 2005), depending on the length of time that the subscriber has paid pension premiums for and the period where an exception has been made for half of the premium value.
http://www.metro.tokyo.jp/ENGLISH/RESIDENT/LIVINGIN/con...