This is a limited production of the SBGC273 Grand Seiko. Only 20 pieces were made for this Grand Seiko retailer in Chiba City, Japan. This watch was available only in Japan.
Congratulations on the SBGC273, that is a great piece. Can you confirm the case code on the back of the watch? It will be the 4 characters after the calibre 9R86-, something like 0AL0