2 Shu 'Kōshū Nishukin'

The Kōshū Nishukin takes its name from Kai Province — historically rendered as Kōshū — where gold mining had been a cornerstone of Takeda clan wealth before Tokugawa Ieyasu absorbed the region following Nagashino. These small gold pieces were produced using gold stocks and minting infrastructure inherited directly from that earlier tradition, making them administratively as much a consolidation of conquered resources as a monetary instrument.

Production is generally attributed to the mid-seventeenth century under the Edo system of licensed gold refiners, the za. The extremely small flan left almost no margin for die error.