japanese: First two hieroglyphs are name of emperor. In this case it is Shōwa (http://en.wikipedia.org/wiki/Hirohito). His reign started in 1926. So 54-th year of reign will be 1925+54 = 1979. This is a year of coin.
1925 instead of 1926 is used because 1926 is a not zero, but first year reigning.
Article about manual years calculations is still in progres. I hope I will finish it in nearest time.