Here is what Sir Sheldon Brown has to say:

" Kabuki - When Japanese bikes were in high fashion, many companies went out of their way to market bikes under Japanese-associated names, including Lotus, Mikado, Shogun, and probably others. Kabuki was a trade name of Bridgestone (a Japanese company with a non-Japanese name!)
The Kabuki line used some unusual construction techniques, specifically, they had a system of sticking the frame tubes into a special mold and forming cast aluminum "lugs" in place around the ends of the tubes. The most notable of this line was the "Submariner" which used un-painted stainless steel tubing, and was marketed in seacoast areas for its rust-resistance. Because the cast aluminum lugs were not flexible like steel lugs, these bikes didn't use a conventional seat-post binder. Instead, they used a seatpost with an expander wedge like that of a handlebar stem...you had to remove the saddle from the seatpost to adjust the height, then re-install the saddle! Even sillier, many of these frames had what looked like a conventional seatpost bolt mounted in a projection of the rigid lug, simply to provide a place to mount a cable stop for the center-pull caliper brake! "