Originally Posted by jtyr71

Here a super rare one: 1975 (or '76?)Kabuki Diamond Road, serial # A623524

Given your serial number guide:
BRIDGESTONE (Japan): Myxxxxx & Fyxxxxx.
F indicates an alpha character designating the fortnight (i.e. A= weeks 1-2, B=weeks 3-4,....Z = weeks 51-52)
M indicates an alpha character designating the month (i.e. A = January, B= February,... L = December)
y indicates a numeric character designating the last digit of the year (i.e. 1 = 1971 or 1981, 2 = 1972 or 1982, etc.). With such codes, you have to determine the decade based on frame characteristics, components, etc.

This bike looks like it was made in early 1976. The OHTS and Japanese characters perhaps identify a particular frame builder?