My mother sent me a picture of a coin she would like identified if possible. Golden in color, reeded edge and light like aluminum. I thank you in advance.
平成二十年 is actually Heisei 20, or 2008. Heisei 12 would read 平成十二年 So the coin is from 2008, not 2000. It is a 500 Yen (五百円) coin from Japan (日本国) as Milesofwho said. It is made of nickel-brass.