1 Ryō 'Kōshū Tsuyu Ichiryōkin'

Kai Province's gold currency predates the Tokugawa unification that would eventually standardize Japanese coinage under the Edo mint system. These pieces were issued under the authority of the Takeda clan — and after Takeda Katsuyori's defeat in 1582, continued under successive administrators of the province. The "Kōshū" designation simply means Kai Province by its classical name, and the "tsuyu" (dew) likely references a quality or purity mark specific to Kai's gold-refining tradition.

Kai's mountainous terrain made it one of the most productive gold-mining regions in sixteenth-century Japan, centered on the Kurokawa gold mines in what is now Yamanashi Prefecture.