Man'en Koban — Japan's Smallest Koban Born of Desperation at the End of the Edo Period

On March 3, 1860, the assassination of Ii Naosuke at Sakuradamon in Edo greatly shook Japan's political situation. This event significantly undermined the authority of the shogunate and had a major impact on both domestic and international economies. Particularly, the imbalance in the gold-silver ratio in trade with Western countries was a problem, with gold being valued at one ryo to five ryo of silver in Japan, whereas it traded at a ratio of 1:15 internationally. Consequently, foreign merchants profited by buying gold on the Japanese market, exchanging it for silver, and taking it abroad. To counter this massive outflow of gold, the shogunate decided to issue a new koban with reduced gold content — the Man'en Koban. On April 10, Man'en 1 (1860), goldsmiths at the government's mint under strict supervision began the minting process. The weight of the new koban was only 3.3 grams, a mere 1/5 of that of the Keichō Koban. This remarkable lightening symbolized the shogunate's predicament and vividly depicted the confusion in the Japanese economy at the time. By lowering the gold's purity to 56.77%, the intention was to keep gold's value low and prevent outflow. Through this policy, the shogunate sought to control the outflow of gold and stabilize the domestic economy. However, this sudden policy change caused confusion among the public, and the impact on the economy was significant. Merchants harbored uncertainties about the value of the new koban, leading to disruptions in trade. The minting of the Man'en Koban continued for about seven years until Keio 3 (1867), showing a glimpse of the shogunate’s trial and error.

The minting of the Man'en Koban was part of the shogunate's economic policy at the time. The minting of gold coins was handled by the Goto family, who managed minting operations during the Edo period. Entrusted with overseeing the mint, the Goto family was responsible for both the technology and quality control of the gold coins. Minting the Man'en Koban required techniques different from regular gold coins. The gold purity was set at 56.77%, with the remainder being 43.23% silver. The reason for reducing the gold content was to curb outflow, but such a gold-silver mix presented a new challenge for minting technicians. The minting facility was set up at the Edo mint, where skilled craftsmen worked tirelessly day and night. Through their hands, small 3.3g gold coins were produced one after another and released to the market based on the shogunate's policy. During this minting process, strict inspections were conducted to maintain quality, ensuring high-quality koban that honored the Goto family’s reputation. The Man'en Koban symbolizes a pivotal point in Japan’s monetary history, realized only through the techniques and efforts of the craftsmen involved.

When the Man'en Koban began to circulate in the market, many were surprised by its lightweight and low gold content. Particularly, Edo merchants were skeptical of this new gold coin. Compared to the conventional Keichō Koban details, its value declined significantly, greatly impacting price stability. As the value of gold fell and inflation progressed, the prices of everyday items rose. For instance, the costs of rice and fish skyrocketed, burdening the lives of ordinary people. In the market, there was debate among merchants about how to handle the new koban. With gold purity being low, it was hard to determine its actual value, leading to confusion in transactions. Additionally, the distortion in the domestic gold-silver ratio caught the attention of foreign merchants, who still attempted to export Japanese gold. Amidst such economic turmoil, the Man'en Koban struggled to gain public support, contrary to the shogunate's expectations. Nevertheless, it came to be studied by many historians later on as a symbol of the monetary system shift during the late Edo period.

The Man'en Koban, as a gold coin symbolizing the chaos during the end of the Edo period, had a significant impact on Japan's subsequent currency system. Although minting ended in 1867, Keio 3, Japan's monetary system underwent major changes with the Meiji Restoration. As part of modernizing efforts, the Meiji government reformed the currency system. This reform introduced the value and recognition of modern currency, and new gold coins were issued. The abolition of the Man'en Koban was a step towards breaking away from the old shogunate's economic policies and aiming for a currency system aligned with international standards. The recoinage of new gold coins was designed with international market transactions in mind, with strict control over gold content and quality. As a result, Japan's economy gradually stabilized and became capable of handling international trade. The experience of the Man'en Koban, while able to curb gold outflows temporarily by reducing gold content, ultimately led to economic chaos in the long term. This experience taught later Japanese monetary policy the importance of careful planning and execution.