1 Mon 'Kan'eitsūhō' Copper alloy, 佐 'Sa' reverse

The Kan'eitsūhō series ran for well over a century under successive mints, but the 'Sa' mintmark identifies production at the Sano mint in Shimotsuke Province, authorized during the Kyōhō-era coinage reforms initiated by shōgun Tokugawa Yoshimune. Yoshimune's broader fiscal program sought to reverse the currency debasements of the Genroku period, restoring metallic standards that earlier administrations had quietly eroded to fund court expenditures.

DHJ references 4.115–118 and 4.121 suggest minor die variations within this mintmark group — not unusual given Sano's extended operational period across multiple decades.