Ninjindai Oko Chogin (人参代往古丁銀)
Ninjindai Oko Chogin refers to silver coins minted from 1710 for exclusive use for trade of Korean ginseng, and it was a silver-by-weight standard. Mameitagin (one of Edo-period coins) which corresponded to this coin was not minted, and Ninjindai Oko Chogin is also called Ninjindai Okogin or merely Okogin or Ninjin Chogin. The term 'Oko' means restoration of the grade of Keicho Chogin (a silver oval coin minted in the early Edo period).
The coin has a Chinese character of 寳 (pronounced as ho, which means treasure) and an effigy of the god of wealth named Daikoku on its surface, and its hallmark is the same as that of Hoei Yotsuho Chogin (the silver coin minted since 1711); however, it has no seal of a Chinese character which represents the era name such as '宝,' and the grade of this coin is the same as that of Keicho Chogin.
As Japanese people did not have knowledge about how to grow Korean ginseng, which was expensive because it had excellent beneficial effect used as a medicine in the early Edo period, its supply depended solely on the import from the Korean Peninsula, and the Tsushima Domain was in charge of this trade and the settlement was done by Keicho Chogin. When reminting of currency was done and Genroku Chogin with low silver content was issued in October 1695, the Tsushima Domain did not inform Korea of this reminting and continued to pay for Korean ginseng with Keicho Chogin with good quality; however, it gradually became difficult for the Tsushima Domain to secure Keicho Chogin, so the trade of Korean ginseng was terminated. Afterward, the domain negotiated with the Korean side for two years, and in May 1699, they agreed that the domain should pay additional 27% of the price besides to the stated price when the domain would pay with Genroku Chogin. Considering the amount of contained silver, 25% of the stated price was a proper additional amount, but the reason why this agreement was made was that the Tsushima Domain received a report from the Korean side in which they found out the percentage of silver content did not meet the defined amount after their analysis of the grade.
However, in 1706 the grade of Chogin was further lowered, and the Tsushima Domain tried to negotiate with the Korean side by paying additional payment according to the grade of the silver content; however, along with the low grade of the coin, the amount of ginseng harvested fell because of the bad weather, and so the negotiation fell apart and the Tsushima Domain received a termination notice of the trade from the Korean side again. Responding to the request from the Tsushima Domain, the Shogunate ordered Ginza (an organization in charge of casting and appraising of silver coins during the Edo period) to mint silver coins which had the same grade as that of Keichogin, exclusively for the ginseng trade, in 1710. This was Ninjindai Oko Chogin, and the term 'oko' meant return. It is said that the Tsushima Domain did not use this name in the trade and used another name 'Tokuchugin' (the silver coin minted for special purposes) to avoid misunderstanding for Genrokugin by Korean side; that is, the Tsushima Domain did not want the Korean side to think that payments up to that point was intentionally made by using low quality silver coins.
According to "Ginza Kakitome" (The Record of Ginza), the Shogunate was to hand the Tsushima Domain 1,417 kan (one kan is approximately 3.75 kg) 500 monme (one monme is approximately 3.75 g) of Ninjindai Oko Chogin per year from 1710.
Afterwards, in 1714, Shotoku Chogin, whose grade was the same as the one of Keicho Chogin, was issued, and accordingly, minting of Ninjindai Oko Chogin was abolished as it was no longer needed. However, the Tsushima Domain still did not receive Ninjindai Oko Chogin allocated for the year of 1713 after this reminting, and they thought paying with Shotoku Chogin would hinder the trade because the hallmark differed from that of Ninjindai Oko Chogin although Shotoku Chogin was good quality, and therefore, they petitioned the Shogunate repeatedly for Ninjindai Oko Chogin to be delivered to the Tsushima Domain and they finally received the coin in 1714.
When Genbun Chogin with the silver content of inferior grade was issued in 1736, minting of Ninjindai Oko Chogin was resumed. However, from around that time domestic cultivation of Korean ginseng became enabled as a part of policy in which new industry is encouraged by Yoshimune TOKUGAWA, and consequently, minting of Ninjindai Okogin declined.
Grade of Ninjindai Okogin
Stipulated grade was 80% of silver (12% minus) and 20% of copper.
Quantity of Ninjindai Okogin Minted
The amount of the coin minted from the Hoei era to the time when Shotoku Chogin was issued was 5,337 kan 156 momme 4 bu (20.00 ton). The breakdown of the amount delivered to the Tsushima Domain was 445 kan in 1710 and the stipulated amount of 1,417 kan 500 monme in 1711, 1712, and 1713, but delivery was always delayed one or two years.