Shōtoku Koban (正徳小判) — The Clash Between Arai Hakuseki's Ideals and Reality

Arai Hakuseki was a Confucian scholar who served as a senior shogunate official under Shogun Tokugawa Ietsugu during the Shōtoku era (1711–1716). He promoted a variety of reforms aimed at fiscal reconstruction and social stability. The Shōtoku Koban, issued in 1714 (Shōtoku 4), was the centerpiece of the monetary policy he advanced. Like the Keichō Koban, this coin aimed to restore gold purity to 86.0%, thereby enhancing the credibility of the currency and achieving economic stability. Based on the theory that 'good money drives out bad,' Hakuseki attempted to eliminate debased coins from circulation by introducing high-quality currency. However, the economic conditions of the time were complex, and this plan was not easily realized. The Shōtoku no Chi was set against a backdrop of monetary debasement that had continued since the end of the Sengoku period. To overcome this, Hakuseki carefully drew up his plans and went ahead with issuing the Shōtoku Koban. He believed a review of the contemporary monetary system was necessary and pushed forward with this policy to restore the shogunate's finances. It was expected that coin quality would be recovered and the credibility of the currency improved. Yet the economic impact this brought proved far greater than Hakuseki had anticipated.

The Shōtoku Koban was minted at the Kinza (gold mint) in Edo. The Kinza was a directly controlled shogunate mint managed from generation to generation by the Gotō family, and it was responsible for producing gold coins throughout the Edo period. The Gotō family possessed exceptionally high technical skill, and their minting techniques were passed down through successive generations. Minting at the Kinza involved a complex series of steps: first, gold and silver were alloyed in the appropriate proportions, then poured into molds. The molds were specially designed and painstakingly crafted by the artisans of the Gotō family. The cast coins were further polished and finally completed by stamping the Kinza's mark. The Shōtoku Koban produced in this way had its gold purity restored to approximately 84% (as recorded in the catalogue), returning it to the standard of the Keichō Koban. While this high quality enhanced the credibility of the currency, it also had the aspect of increasing manufacturing costs. For this reason, the issuance of the Shōtoku Koban was accompanied by many challenges. Although technically superior, its high costs would later exert economic consequences. Furthermore, from records of the time it is clear that while the skill and efforts of the Kinza's artisans supported the shogunate's finances, their own lives were also difficult.

The issuance of the Shōtoku Koban sent unexpected ripples through the Edo economy. As high-purity gold coins entered circulation, prices fell sharply and the economy contracted. Contrary to Hakuseki's intentions, this came as a severe blow to commoners and merchants alike. In Edo at the time, money changers who exploited the price differential between gold and silver were actively operating, and they found themselves unable to profit from the circulation of the new coins. It is said that merchants sometimes appealed to the shogunate seeking price stability. For commoners too, falling prices were a matter directly tied to their livelihoods; in rural areas in particular, rice prices dropped and farmers' incomes plummeted sharply. Such economic turmoil was also connected to silver coinage, with the relative decline in the value of silver coins also playing a role. The issuance of the Shōtoku Koban was not merely a monetary policy matter — it produced effects that spread across the whole of society. How did people cope under such circumstances? Merchants sought new business models, while commoners were compelled to economize. The shogunate also took this situation seriously, leading to the reexamination that would connect to the later Kyōhō Reforms. In this way, the Shōtoku Koban exerted a major impact on the economy almost immediately after its issuance, and that impact extended into the lives of ordinary people.

Several years after the issuance of the Shōtoku Koban, Tokugawa Yoshimune came to advance the Kyōhō Reforms. Yoshimune learned from the failures of the Shōtoku Koban and sought to overhaul the monetary system. He pursued policies aimed at economic stability while maintaining gold purity. The Kyōhō Reforms aimed to stabilize prices by maintaining the quality of coins while adjusting the volume in circulation. Drawing on the lessons of the Shōtoku Koban, Yoshimune's reforms succeeded in implementing more pragmatic policies. Through these reforms, the economy gradually stabilized, and merchants were able to seek new business opportunities. Commoners' lives also stabilized, and society as a whole gradually returned to tranquility. The monetary policy of the Shōtoku Koban became an important lesson in Yoshimune's reforms, and new monetary policies were formulated in light of its failures. Even today, the Shōtoku Koban is cited as an important example in the history of economic policy. A reassessment of the historical significance of the Shōtoku Koban is called for. As a coin that embodies both the failure and success of monetary policy, it will continue to serve as an important lesson for monetary policy in later ages.