The Japanese Government is adopting a new Social Security and Tax Number System and will start to send out notices containing residents' "Individual Number" or "My Number" starting October 2015.
Both Japanese and non-Japanese residents of Japan will receive a notice in the post from their Ward Office containing their new identification number. Please be sure to keep this notice safe as you will need to provide your number on application forms and other documents when processing national pension, unemployment insurance, medical insurance, child allowances, welfare benefits and taxation procedures.
More information on the new system can be found here: http://www.kojinbango-card.go.jp/en/index.html (English)
For phone inquiries please call T 0570-20-0291 (service available in six languages: Japanese, English, Chinese, Korean, Spanish, and Portuguese. Service hours: 9:30 a.m. to 5:30 p.m.