Wikipedia
Dōza
was the Tokugawa shogunate's officially sanctioned copper monopoly or copper guild ( za) which was created in 1636 and (1701-1712, 1738-1746, 1766-1768).
Initially, the Tokugawa shogunate was interested in assuring a consistent value in minted copper coins; and this led to the perceived need for attending to the supply of copper.
This bakufu title identifies a regulatory agency with responsibility for supervising the minting of copper coins and for superintending all copper mines, copper mining and copper-extraction activities in Japan.