1000 Yen MS70,2015 The 60th anniversary of the implementation of the Local Autonomy Law Japan 2015 Chiba Prefecture 1000 Yen, Silver Coin. Issued in 2010 (Heisei 27) to commemorate the 60th anniversary of the enactment of the Local Autonomy Law, this set includes a single pure silver coin with a face value of 1000 Yen, weighing approximately 31.1 grams and measuring 40mm in diameter. Designs vary depending on the prefecture.