Sanbungin — The Experimental Silver Coin from the Tenpō Reforms

In the 6th year of Kaei (1853), the appearance of black ships on Japan's coast, demanding the opening of the country, shocked Japanese society. During this tumultuous era, the shogunate attempted various reforms to stabilize its economic base. As part of this, the shogunate decided to mint a new silver coin, the Sanbungin. This coin had a face value equivalent to 3/4 of one gold ryō and featured an unusual rectangular shape. This shape represented a new experiment in the silver coin market of the time, with the shogunate's intention being clear; it was to address the increased demand for silver due to the expansion of foreign trade. As part of the Tenpō reforms, a review of the monetary system was carried out, and Sanbungin became a symbolic presence of this effort. However, contrary to the shogunate's intent, the economic confusion following Perry's arrival and rebellions and disturbances across the land hindered the distribution of Sanbungin. Opinions within the shogunate were divided, and amid political confusion, the presence of Sanbungin gradually faded away. Nevertheless, the decision to mint it reflects the shogunate's desperate attempts at experimentation under the external pressure of Perry's arrival. Sanbungin can be seen as an experimental product created by the shogunate under such external pressures.

The minting of the Sanbungin was carried out in Edo's Kinza by order of the shogunate. Kinza was the institution responsible for coin minting during the Edo period, and technicians worked under the strict supervision of the shogunate. Sanbungin was made from an alloy of 80% silver and 20% copper, a standard composition among silver coins of the time. However, its rectangular shape was unique, requiring special technology for minting. This shape was innovative for currency at the time, posing a new challenge for the minting technicians. Many workers were involved in minting, among them craftsmen with exceptional skills. The process involved first melting the silver-copper alloy, pouring it into molds to create rectangular ingots, cutting these into fixed sizes, polishing the surfaces, and finally stamping them. Despite this labor-intensive process, the circulation of Sanbungin faced difficulties from the start. Contrary to the shogunate's expectations, the changing regional and economic conditions made it hard for Sanbungin to maintain its presence. The technicians involved in minting personally experienced the shifts in the monetary system during the chaotic late Edo period.

When Sanbungin appeared on the market, its unique shape and face value attracted attention. However, problems arose soon after it began circulating. In the chaotic economic situation of the late Edo period, with fluctuating silver coin values, the circulation of Sanbungin did not proceed as expected. Particularly after the port openings in 1854, exchange rates with foreign currencies fluctuated, spreading distrust of Sanbungin's value among the populace. Many merchants avoided using Sanbungin to profit from exchange rate differences. Additionally, its large denomination made everyday transactions inconvenient, leading to poor acceptance among the common people. This situation resulted in a decline in trust towards Details of Keichō Koban and previous monetary systems. Moreover, opinions within the shogunate about Sanbungin were divided, with some advocating for its continued circulation and others calling for its swift abolition. Amidst such circumstances, Sanbungin gradually disappeared from the market, with its circulation lasting only a little over a decade. Nevertheless, its rarity has increased its value in modern times.

Despite its short historical lifespan, Sanbungin's influence on later generations was significant. Although it had low practicality as a silver coin, its unique rectangular design is said to have influenced later coin designs. Especially during the coinage system reforms after entering the Meiji era, its existence attracted the attention of some officials and numismatists. Compared to other silver coins in circulation at the same time, like the Ichibugin and Ichishugin, opinions on Sanbungin varied, but its rarity leads collectors with Basic Knowledge of Coin Auctions to highly value it. When the Meiji Government reformed the monetary system, it is believed that they learned many points from Sanbungin's failure, particularly the necessity for design considering circulation and user convenience. Additionally, in modern times, Sanbungin is traded at high prices due to its historical value and rarity, making it a coveted item among collectors. Through Sanbungin, one can interpret the transitions in the monetary system from the late Edo to the Meiji period and the political and economic situations behind them.