I think I found out a little bit more on the bike. It has characteristics of a 70's Sekine. It has the same crank setup as a sekine(Aluminum SR arms w/ 75.7 stamped on them), The frame is all steel possibly Chromoly lugged. The brakes are aluminum Diacompe w/ safety lever type, Aluminum Handlebars& stem (SR ). I was wrong about the serial number. It looks like a squarish "D" and then 129088 stamped on bottom of BB.