Wartime 10-sen Aluminum Coin — A Witness in Metal Reflecting Tumultuous Times

In the late 1930s, Japan faced increasing international isolation and the prolonged Second Sino-Japanese War led to a steady depletion of national strength. The war, which began in 1937, had become mired in a stalemate, inflating military spending to over half of the national budget. With the outbreak of World War II in 1939, international tensions further intensified. Japan had to strengthen its national mobilization system to prepare for the forthcoming large-scale conflict. During this period, securing strategic resources, particularly metals essential to the arms industry, became a top national priority. Rare metals like copper, nickel, and silver were heavily consumed in the production of munitions, artillery shells, aircraft, and ships, causing their stockpiles to dwindle daily. The Ministry of Finance implemented various measures to minimize civilian metal consumption and redirected it for military use, one being the review of coin materials. In 1939, the 'Gold Coin Retrieval Order' was issued to secure national gold reserves, mandating the forced recovery of gold coins owned by the public. On March 27, 1940, the 'Amendment to the Currency Act' was announced, deciding to switch the 10-sen coins from cupronickel (copper 75%, nickel 25%) to aluminum from April 1, Shōwa 15 (1940). This decision stemmed from the critical importance of nickel in military applications, necessitating its complete removal from coin use. The Konoe Fumimaro Cabinet sought ways to minimize the impact on civilian life while maximizing resource diversion for military purposes. Aluminum, with its increasing domestic production capacity at the time, was deemed less strategic compared to copper and nickel. This amendment led to the production of the new aluminum 10-sen coins, signaling an era of unprecedented circumstances like the upcoming Pacific War, as witnesses of the time. For more information on Edo period gold coins, see Types and Identification of Edo Gold Coins.

The selection of aluminum as the new material was due to its lightness and good workability. However, maintaining its durability as a coin and compatibility with the existing monetary system posed new challenges for the Ministry of Finance Mint Bureau. At the Mint Bureau in Kita-ku, Osaka, technicians tirelessly researched the production of the new 10-sen aluminum coin. Compared to traditional cupronickel or bronze coins, aluminum was very soft and prone to wear, requiring the use of an aluminum alloy with small amounts of copper and magnesium to increase strength. Despite these efforts, the severe wartime resource shortages likely made it challenging to maintain quality. In terms of design, the coin featured the 'Rising Sun' on the obverse and the 'Paulownia Crest' on the reverse. The Rising Sun symbol, long used as a symbol of Japan, expressed the power of sunrise and aimed to boost the morale of the wartime population. The paulownia crest was considered a noble emblem second only to the chrysanthemum and indicated a connection to the Imperial Family. These designs were fitting for wartime currency, evoking national prestige and patriotism. In 1940, approximately 240 million coins were minted, 250 million in the following year, 450 million in 1942 when the Pacific War commenced, and about 300 million in 1943, with production increasing annually. The dedicated efforts of Mint Bureau craftsmen supported this massive production under strict resource control and challenging labor conditions, fulfilling the crucial mission of national currency supply. Resulting from Japan's wartime technical prowess amid constraints, the 10-sen aluminum coin stands as a historical testament. For more on Hōsen (holed coins), refer to Types and Identification of Holed Coins.

The wartime 10-sen aluminum coin, introduced in 1940, quickly circulated throughout Japan, deeply embedding itself into the daily lives of ordinary people. The Japanese economy of the time, influenced by the prolonged Second Sino-Japanese War and escalating international tensions, began to show signs of inflation. Prices gradually increased, making it notably difficult to acquire essential goods and foodstuffs. The government issued the 'Price Control Order' in 1939 to curb prices, but in practice, black markets flourished, widening the gap between official and actual market prices. The aluminum coin, while easy to handle due to its lightness, initially sparked doubts among some who wondered if such a lightweight item could truly be currency. However, as other metal coins began to vanish over time, aluminum coins became indispensable. Following the outbreak of the Pacific War on December 8, 1941, the national mobilization system was further reinforced, with nationwide campaigns for metal contributions from households, religious sites, and everywhere else for 'the country's sake.' This included currency metals. In everyday wallets, the 10-sen aluminum coin was frequently used for small purchases: a pack of cigarettes (about 10 sen at the time), a matchbox (about 2 sen), a bus ride (starting fare of 5 sen), and for purchasing rationed goods like rice and sugar. However, as resource scarcity worsened, the value of currency itself relatively declined. For instance, the official price of rice was about 3 yen per 10 kg in 1940, but it often traded for several times that amount on the black market. During this period, people lived with resource shortages and the anxiety of an endlessly uncertain war. The aluminum coin passed from hand to hand, its light jingle supporting modest purchases amid the harsh realities of wartime life. To correctly assess the value of old coins, it helps to know How to Identify Counterfeits and Altered Coins.

By 1943, the tide of the Pacific War had increasingly turned unfavorably for Japan. Defeats such as the Battle of Guadalcanal and the catastrophic blows from the Battle of Midway exacerbated metal shortages, prompting another review of coin materials. Even aluminum began to be prioritized as a strategic resource for aircraft production. Consequently, from 1943 onwards, the material for the 10-sen coin was changed to tin. By 1944, due to the extreme shortage of metal resources, ceramic 10-sen coins (tōka) unprecedentedly appeared. These material changes vividly illustrate Japan's dire wartime situation. The wartime 10-sen aluminum coin completed its role in a short span of just four years, passing the baton to more readily available and inexpensive materials. Post-war, Japan's economy endured massive chaos, with rampant inflation. In February 1946, the government implemented deposit freezes and new currency exchanges, halting the circulation of old coins. The wartime 10-sen aluminum coin officially concluded its role during this currency exchange, becoming buried in history. However, its historical significance remains undiminished. Today, the wartime 10-sen aluminum coin is cherished by many collectors as a precious historical document symbolizing Japan's turbulent Shōwa history. Its light touch and designs of the Rising Sun and paulownia silently narrate the hardships faced by the nation's people and the weighty destiny borne by the state. Compared to its successors like tin or ceramic coins, the aluminum coin was among the last to maintain the bare minimum of metallic dignity. This coin is not merely a means of payment but a bearer of the memories of people who lived through the maelstrom of war, serving as a witness to history. For the coin grading criteria, see Grading Criteria for Old Coins for more details.