Wartime Tin 5-Sen Coin — A Lightweight Coin Born of Late-War Privation

In 1944, Japan was entering a grave phase of the Second World War. By Shōwa 19, the depletion of resources had become pronounced, and the use of copper and nickel that had been standard until then grew increasingly difficult. In particular, the loss of naval supremacy in the Pacific theater disrupted the transport of raw materials from Southeast Asia, severely constraining the supply of metals to the Mint (Osaka). The government therefore decided to mint coins using tin, which was comparatively easier to obtain at the time. Because a certain quantity of tin could be expected to be secured from occupied territories such as the Malay Peninsula, it was adopted for two denominations: the 10-sen and 5-sen coins. Thus the tin 5-sen coin was born. The Japanese government of the time, acting under the name of Emperor Shōwa, demanded strict saving and frugality from the populace in order to allocate resources efficiently. The 5-sen coin was symbolic of this, and its lightness of just 1.0 g and small diameter of 19 mm plainly reflected the deprivation of wartime Japan. Minted in 1944, this coin subsequently circulated alongside the tin 10-sen coin. As the war dragged on, prices soared and the face value of 5 sen gradually lost its purchasing power in the daily lives of ordinary people; nonetheless, the coin continued to play a part in the country's economic circulation. After the end of the war it remained in circulation for a time, but it was demonetized by the new-yen conversion implemented in 1946 (Shōwa 21), bringing its brief role to a close. For more detail on the economic conditions of the wartime period, please see Details on the Keichō Koban (慶長小判).

The minting of the 5-sen coin was the crystallization of Japan's technological capability at the time. Minting was carried out primarily at the Osaka Mint, where technicians poured their efforts into producing high-quality coins from limited resources. Tin, as a metal, is soft and easy to work but lacks durability, so specialized techniques were required for minting. Craftsmen made fine adjustments to casting temperature and cooling speed in order to preserve the coin's strength while making use of tin's properties. Minting of the coin, which began in Shōwa 19 (1944), was set to the compact specifications of 1.0 g in weight and 19 mm in diameter. At a time when metals such as copper and nickel were being requisitioned as priority military supplies, tin attracted attention as a comparatively obtainable metal; together with the tin 10-sen coin issued the same year, it was adopted for two types of subsidiary currency: the 5-sen and the 10-sen. The design of the tin 5-sen coin was emblematic of wartime simplicity: on the obverse the characters「五銭」are inscribed, and on the reverse the chrysanthemum crest. This design reflected the militarism of Japan at the time and was meant to project the dignity of the state. The minted coins subsequently circulated nationwide and supported Japan's wartime economy. Even after Japan's defeat in August 1945 (Shōwa 20), the tin 5-sen coin continued to circulate for a time as legal tender, but it was demonetized by the new-yen conversion implemented in 1946 (Shōwa 21), bringing its brief role to a close. Those who wish to learn more about the minting techniques of the tin 5-sen coin may refer to Types of Edo Gold Coins and How to Identify Them.

How did the 5-sen coin circulate in wartime Japan? The economy of the time was suffering under material shortages and inflation caused by the war. The tin 5-sen coin issued in 1944 (Shōwa 19), though compact at 1.0 g in weight and 19 mm in diameter, played an important role in everyday transactions; in practice, however, its value was declining rapidly. Due to soaring prices, a face value of 5 sen was of little use for purchasing daily necessities. Even so, this coin was indispensable for small-value transactions, and was still widely used especially in regional markets.

Behind the adoption of tin as a material was the fact that metals such as copper and nickel were being requisitioned as priority military supplies. The Treasury Mint, having explored alternative materials, chose tin — which was comparatively obtainable within the domestic circulation of the period — and adopted it for two denominations: the 10-sen and the 5-sen. However, as the war situation deteriorated, the supply of tin itself became unstable, and it is said that maintaining production quantities and quality posed considerable difficulties (accounts vary).

After the war, when the new-yen conversion was implemented in February 1946 (Shōwa 21), existing banknotes and coins were progressively demonetized, and the tin 5-sen coin was among them. The new-yen conversion was an economic measure centered on the issuance of new Bank of Japan notes and the freezing of deposits on old notes, carried out with the aim of suppressing rampant inflation. Until it was demonetized, the tin 5-sen coin continued to circulate even through the confusion of the immediate postwar period. The economic conditions of this era have been analyzed from various perspectives by historians and economists. For information on the economic situation and currency circulation during the war, please also refer to Types of Holed Coins and How to Identify Them.

The wartime tin 5-sen coin continued to circulate for a time after the end of the war, but was officially abolished by the new-yen conversion of 1946 (Shōwa 21). This new-yen conversion was implemented in March of that year, and existing currency was successively collected and demonetized. The coin subsequently came to occupy an important place in Japan's postwar monetary history. As a coin issued during wartime, its historical value began to be reassessed in postwar Japan. Collectors recognized it as a symbol of the horrors of war and the hardships endured by the people, and its collectible value grew. In particular, the small tin form — weighing just 1.0 g with a diameter of 19 mm — has attracted the attention of numismatic researchers as evidence of the resource shortages of 1944 (Shōwa 19), when copper and cupronickel were being compelled into military requisition. Together with the tin 10-sen coin issued at the same time, the circumstances under which tin was adopted for two denominations — the 5-sen and the 10-sen — as a comparatively obtainable metal are evaluated as primary source material illustrating the realities of wartime economic policy. The wartime tin 5-sen coin occupies a unique place in modern Japan's monetary history: against a backdrop of war, it nonetheless fulfilled the role of supporting the daily lives of the people. The significance of this coin's issuance and circulation is a testament to how postwar Japan looked back on its past and began to move forward toward the future. Even today, coins with such historical backgrounds are popular among collectors, and particularly fine specimens can change hands at high prices. For the historical significance of the wartime tin 5-sen coin, please also refer to Basic Knowledge of Old Coin Auctions.