Nanryō Nishugin — The Edo Innovation Brought by the Currency Revolution of Tanuma Okitsugu

In the mid-Edo period, with Tanuma Okitsugu at the center of power as a senior counselor in Meiwa 9 (1772), Japan's economy was shifting from agriculture-centered to commerce-centered. Tanuma decided to reform the currency system to promote commerce. His goal was to achieve more efficient economic circulation. The previous weighing silver coins required weighing at each transaction, causing inconvenience and time consumption. Therefore, Tanuma attempted to solve this issue by introducing the fixed-amount silver coin 'Nanryō Nishugin'. These silver coins were equivalent in value to 1/8 of one gold ryō, and were inscribed with '以南鐐八片換小判一両'. This inscription indicated that eight Nanryō Nishugin coins could be exchanged for one koban ryō, making them extremely convenient for merchants. Tanuma's policy seemed groundbreaking, but his bold reforms also led to backlash. Particularly, inadequate currency circulation in rural areas resulted in economic disruption. Tanuma's policies continued from 1772 to 1786 but were temporarily halted upon his downfall; nonetheless, Nanryō Nishugin contributed to commercial development, laying the foundation for later currency systems.

The minting of Nanryō Nishugin gathered the most advanced technology and skilled craftsmen of the time. Minting was mainly carried out at the gold mint in Edo, with strict quality control standards for silver. 'Nanryō' refers to high-quality pure silver, and advanced techniques were used in silver refining to live up to the name. The silver was first refined to remove impurities, then rolled to uniform thickness, and poured into molds. In designing the Nanryō Nishugin, attention was also paid to the beauty of the engravings on the surface. The engraving '以南鐐八片換小判一両', crucial information indicating that eight Nanryō Nishugin equate to one koban ryō, was meticulously applied to each piece by skilled artisans. The involvement of renowned craftsmen from families like the Goto family is suggested, but the details remain debated and not entirely elucidated. Under Tanuma Okitsugu's guidance, these associates honed their skills to realize a new monetary system, resulting in the innovative Nanryō Nishugin. Thus conceived, it was a groundbreaking fixed-amount silver coin at the time, significantly influencing later currency system reforms.

The advent of Nanryō Nishugin caused significant changes in the Edo-period market. The introduction of fixed-amount silver coins facilitated smoother commercial transactions, invigorating circulation particularly in commercial hubs like Edo and Osaka. With a fixed value equivalent to 1/8 of one gold ryō, the coins eliminated the need for weighing and were extremely convenient for merchants. This improved transaction speed and stimulated commercial activity. Prices stabilized, promoting economic development, especially in urban areas. However, the change had adverse effects in rural areas. Insufficient currency circulation led to rising prices, causing hardship for many farmers. The spread of Nanryō Nishugin widened economic disparities between urban and rural areas, receiving criticism for this effect. While Tanuma Okitsugu's policies aimed at commercial development, their impacts were not uniformly beneficial. Nevertheless, the introduction of Nanryō Nishugin advanced commerce, laying the groundwork for a modern monetary system. Leading towards the late Edo period, Japan's economy progressed to a new stage.

Nanryō Nishugin greatly influenced Japan's subsequent currency systems. Although abolished in 1824 with the advent of the Bunsei Koban, the concept of fixed-amount currency was carried into later systems. The success of Nanryō Nishugin emphasized the importance of currency standardization and smooth circulation, forming the basis for subsequent currency reforms. Specifically, the yen-sen-rin system in the Meiji era's New Currency Ordinance partially adopted the fixed-amount concept, smoothing the transition to modern Japan's currency system. Additionally, the importance of minting technology and quality control demonstrated by Nanryō Nishugin was inherited by later currency system reforms. It was not merely a silver coin but a symbol of the evolution of Japan's currency system. Tanuma Okitsugu's reforms continued to influence Japan's economy beyond his lifetime. His commercial promotion policies undoubtedly contributed to Japan's economic development across ages.