All persons living in Japan are required to enroll in the National Pension Plan and a Social Insurance plan, so it is important to familiarize yourself with each of these systems and how they affect you.
For basic information regarding the Japanese Pension service, please refer to the special pension information page provided by the Council of Local Authorites for International Relations (CLAIR).
The Japan Pension Service
The Japan Pension Service's English page provides detailed information about coverage, benefits, and contributions of the various plans. Informative PDFs are also available.