Yeah David. What's the deal with the dog headbadge? Really I do know a little bit about the Mizutani Super beyond the cool bronze head badge. Mizutani was a bike boom importer when Japan actually built and exported bikes. They certainly were no Fuji in terms of sheer numbers imported. In fact, the number of Mizutani bikes that found their way to our shores was pretty small. The Mizutani Super was the top of the line back in the early to mid 70's. They used double butted Tange Prestige tubing, Nervex like lugs (sometimes chromed), and the best components Japan had to offer. Your bike still has the somewhat rare Dura Ace center pull brakes, a very early Dura Ace Crank, a Titelist front and possibly a Crane rear mech. It should have ARY rims and early Shimano high flange hubs. The bike came with Toyo sew-ups. The pedals were Mikashima road. The shifters were Dura Ace bar end, and Nitto stem and bars. The Brooks pro saddle is obviously not original to the bike, a Fujitsu Cinnelli copy came with the bike fixed to a no name alloy seatpost. A 53 cm Mizutani Super weighed in at about 21 lbs. Your dumpster bike cost more than a PX 10 Peugeot in 1973 the year I think your bike was built.
Chris Van Scoyk