In 1961, a national pension exclusively for Japanese people was established. At the time of its establishment, the ages of eligibility were twenty to sixty years old. In order to include all citizens, two measures were introduced. One shortened the required enrollment period of the pension for those who were between thirty-one to forty-nine years old. The other provided a senior welfare pension for those who were older than fifty years of age, and allowed the receipt of a pension without the payment of a premium. When the Ogasawara Islands and Okinawa (the Ryukyu Islands and the Daito Islands) were returned to the Japan, the Japanese government enacted legislation similar to as when the national pension was established so that people of tho...