Eiraku Tsūhō (永楽通宝) — The Journey of a Chinese Coin That Adorned the Muromachi Period

The background to the Ashikaga Shogunate's adoption of the Eiraku Tsūhō was shaped by the political and economic conditions of the time. During the Muromachi period, Japan was in a state of fragmentation, and the authority of the central government was wavering. Ashikaga Yoshimasa (1449–73) needed to implement economic stabilization measures to restore the shogunate's authority. It was in this context that the Eiraku Tsūhō, an import from China, came to be noticed. The Eiraku Tsūhō was a coin whose minting had begun under the Ming dynasty's Yongle Emperor, who had ascended the throne in 1403, and its abundant circulation domestically was anticipated. Particularly after the Ōnin War, which began in 1467, there was a domestic shortage of coinage, and the introduction of the Eiraku Tsūhō contributed to economic stabilization. Ashikaga Yoshimasa positioned this copper coin as the key currency and encouraged its nationwide circulation. As a result, the accounting unit 'Eiraku-zeni-daka' spread throughout eastern Japan in particular and became the standard for commercial transactions. In an environment where the Eiraku Tsūhō circulated in eastern Japan while Song coins and Ming coins coexisted in western Japan, the Eiraku Tsūhō was widely accepted among merchants and commoners alike due to its reliability and stability. A detailed explanation of the Wadō Kaichin makes the evolutionary process of such currencies all the clearer.

The minting of the Eiraku Tsūhō was carried out under the centralized system of the Ming dynasty, and the coins flowed into Japan primarily through trade. By order of the Ming dynasty's Yongle Emperor, full-scale minting began in 1403, and the coin became an important currency supporting the economic foundations both within China and abroad. Imports to Japan increased sharply from the 1460s onward, and particularly during the reign of Ashikaga Yoshimasa, large quantities were circulated through the hands of merchants. During this period, Japan's domestic production had stagnated due to repeated internal conflicts, and dependence on imported coins was increasing. In port towns such as Sakai and Hakata in particular, the Eiraku Tsūhō was actively traded and supported commercial development. The primary minting sites were centered in the Jiangnan region of China, and a high level of technical skill was required. Copper was the main material used, and it is said that strict standards were set for the alloy composition. Within Japan, supervision was carried out through coin mints held by the shogunate in order to promote the circulation of this currency. The circulation of the Eiraku Tsūhō also underpinned the economic foundations of the Sengoku daimyo and became one factor in the formation of distinct regional circulation zones. The formation of these circulation zones later connected to Toyotomi Hideyoshi's currency unification policy, and by comparing with the Value and Identification of Modern Currency, the evolution of monetary policy can be understood.

The Eiraku Tsūhō had a profound impact on the Japanese economy during the Muromachi period. Particularly during the reign of Ashikaga Yoshimasa, the Eiraku Tsūhō contributed to economic stabilization and promoted commercial development. During this period, the shortage of currency became serious, and domestic coin production alone could not meet demand. It was thus that the Eiraku Tsūhō, an imported coin from Ming China, became the foundation supporting Japan's economy. Merchants used this coin to conduct transactions, and its value was recognized especially in major commercial cities such as Kyoto and Kamakura. The introduction of the accounting unit 'Eiraku-zeni-daka' promoted the standardization of commercial transactions and brought about greater efficiency in economic activity. Prices stabilized and markets regained their vitality. Trust in the Eiraku Tsūhō also grew among the general populace, and ordinary people began using this coin for everyday purchases and transactions. In an environment where the Eiraku Tsūhō circulated in eastern Japan while Song coins and Ming coins coexisted in western Japan, the circulation of the Eiraku Tsūhō became a factor supporting the expansion of commerce. This led to the formation of distinct circulation zones within each daimyo domain across Japan and to the development of commercial networks. Such economic impacts would eventually come to influence monetary policies such as those described in Details of Edo Silver Coins.

The Eiraku Tsūhō also influenced the subsequent history of Japanese currency. Having established its position as the key currency throughout the Muromachi period, the Eiraku Tsūhō further strengthened that position as the Sengoku period began and daimyo formed their own independent economic spheres. However, as time progressed, Toyotomi Hideyoshi's currency unification policy was launched and the multiple circulation zones came to an end. Hideyoshi sought to stabilize the economy by constructing a unified monetary system, and as a result, traditional coins including the Eiraku Tsūhō gradually disappeared. Entering the 1590s in particular, Hideyoshi advanced the unification of gold and silver coinage, and new currencies such as those described in Details of the Keichō Koban were introduced. Through this policy, the Eiraku Tsūhō was excluded from circulation, yet its influence remained in later ages. The circulation of the Eiraku Tsūhō contributed to the development of regional economies and the formation of commercial networks, and it played a part in establishing the economic foundations of modern Japan. Today, the Eiraku Tsūhō is a popular ancient coin among collectors owing to its historical value and is also appreciated as a cultural property of historical significance. The evolution of such currencies serves as a key to understanding the overall flow of monetary history as described in works such as An Overview and Appeal of Ancient Currencies.