What Are Temporary Auxiliary Coins: The Unique Coins Born from Wartime Economy
In the Showa 20s (1945-1954), a series of "temporary auxiliary coins" made from alternative materials to replace the normal copper and nickel were issued against the backdrop of depleted metal resources due to the Pacific War and post-war material shortages in Japan. These coins, which started as "temporary" measures, continued to function as official currency through the period of occupation and the recovery of independence, marking a rare presence in currency history. The main types are as follows: ① Aluminum coins from Showa 12 to 16 (1 sen and 5 sen): adopted lightweight and easy-to-work-with aluminum. ② Tin coins from Showa 18 to 19 (1 sen): grayish white coins primarily made from tin. ③ Ceramic coins from Showa 19 to 20 (1 sen and 5 sen): unprecedented ceramic coins. ④ Aluminum auxiliary coins from Showa 21 to 25 (50 sen and 1 yen): simple coins during post-war inflation. The overall positioning of these is organized under Overview of Modern Coins.
Ceramic Coins: An Unprecedented Material Choice in the World
Among the temporary auxiliary coins, the ceramic coins issued between Showa 19 (1944) and Showa 20 (1945) stand out uniquely. Two types, "ceramic 5 sen coin" and "ceramic 1 sen coin", were made, featuring the chrysanthemum crest and denomination in blue glaze on white porcelain or grayish white ceramics. In the world's currency history, examples of ceramic coins as official state currency are extremely rare, alongside the "emergency currency (Notgeld)" pottery coins tried by Germany during World War I, making them notable curiosities in numismatics. The issuance background was a simple metal shortage, with a stronger improvised significance rather than practicality. In practice, many were stored without being used due to their fragility and low circulation, meaning that many existing specimens are relatively well-preserved. However, completely uncirculated specimens (UNC) are by no means numerous, and those with well-preserved sets have increased in collectible value.
Tin Coins and "Su" Mark Aluminum Coins: Reading the Material Transition
The tin 1 sen coins issued between Showa 18 and 19 represent Japan's first use of tin as official currency. The chrysanthemum crest and "大日本" "一銭" characters are cast on the surface, but the dark gray texture unique to tin differs from normal copper coins. Although easier to process than copper due to its lower melting point, tin easily oxidizes and produces white rust, making well-preserved items rare. The "aluminum 5 sen coins" manufactured from Showa 16 have variations with a small imprint "Su" (an abbreviation for tin) under the paulownia crest on the reverse. This "Su mark" is said to signify a manufacturing mark for tin-plating, and its details are subject to collector research. Understanding these material transitions is important as a direct connection to the decline in quality from the Taisho to Showa periods, which is explained in the article Transition of Quality in Modern Japanese Coins.
Post-War Reconstruction Aluminum Auxiliary Coins: Battle Against Inflation
Between Showa 21 (1946) and Showa 26 (1951), aluminum 50 sen and 1 yen coins were issued during the rapid post-war inflation. During this period, Japan was under the occupation of the Supreme Commander for the Allied Powers (GHQ/SCAP), and even currency issuance policies were indirectly influenced by the GHQ. The "aluminum 1 yen" issued from Showa 21 to 23 is characterized by the chrysanthemum crest and the old character "一圓", weighing about 1.0g, nearly the same as modern 1 yen aluminum coins (1.0g). However, following the Dodge Line economic stabilization policy in 1949, as inflation began to settle, the currency issuance system also moved towards normalization. With the "Minor Currency Sorting Act" of 1953 (Showa 28), auxiliary coins under 1 yen were abolished, ending the historical mission of these temporary auxiliary coins. This entire sequence is a microcosm of Japan's post-war economic history and holds educational value as material for learning history through currency.
Market Price and Rarity Status
The market price of temporary auxiliary coins from the Showa 20s varies greatly depending on the type and condition. Below are guidelines from the 2020s in specialty stores and auctions. War-time aluminum small coins (1 sen and 5 sen), average condition: around a few hundred to 1,000 yen. Tin 1 sen coin, fine condition: 3,000 to 10,000 yen. Ceramic 5 sen coin, fine condition (without cracks): 10,000 to 30,000 yen. Ceramic 5 sen coin, completely uncirculated (UNC): 50,000 to 150,000 yen (rare). Ceramic 1 sen coin, fine condition: 5,000 to 20,000 yen. Ceramic set (1 sen + 5 sen, matched condition): 30,000 to 80,000 yen. Noteworthy is the ceramic coins, with rising demand amid the recent "wartime and occupation collection" boom. Particularly, UNC ceramic 5 sen coins are becoming harder to acquire, and regular auction rounds are effective. Aluminum coins are abundant in number and have low expected value as investment targets, but there is demand for them as part of "complete set collections." The basics of value evaluation can be referenced in Factors Determining the Value of Old Coins.
Collectors' Theme: Systematizing Wartime to Occupation Era Coins
The temporary auxiliary coins of the Showa 20s are popular among collectors as a "wartime and occupation theme collection." Specifically, the following collection axes can be considered. ① "Material-Based Collection": Collect one piece each of ceramics, tin, aluminum, and cupronickel. The diversity of materials not experienced in any other aspect of Japanese numismatic history is attractive. ② "Year-Based Collection": Collect one piece from each issuance year from Showa 12 to Showa 26. Experience the changes of inflation, occupation, and independence through years. ③ "Same Denomination Chronological Collection": Focused on "5 sen coins", gather silver coins (Taisho period) → aluminum → ceramics → abolition at once. Enjoy the dramatic material changes visually. The appeal of theme collecting is that it allows creating a systematic "story of a collection" without chasing high-priced items. Reading in conjunction with Approach to Commemorative Coins and Special Year Collection and Difference Between Investing and Collecting can help design your own collecting style.
Authenticity and Preservation: Tips Specific to Ceramic Coins
Compared to high-value metal coins, the temporary auxiliary coins of the Showa 20s are less likely to circulate with sophisticated counterfeits. However, there are specific points to note. For ceramic coins, ① the presence or absence of "cracks" is the most critical state assessment factor. Fine cracks characteristic of ceramics indicate the risk of breakage and lead to significant devaluation. Inspect the entire perimeter under bright light when purchasing. ② Chips. Small chips on the edge are common in ceramics, but those affecting face value or crest characters result in major devaluation. Tin coins face ③ "white rust" (whitish powdery oxides) as the main form of deterioration. Coins with advanced white rust have their surfaces eroded, greatly reducing their value. When storing, using silica gel desiccant for moisture protection is essential. Aluminum coins are relatively stable, but those with ④ "polishing or cleaning marks" are marked down during appraisal. For storage methods of temporary auxiliary coins, refer to Proper Storage Methods for Ancient Coins.
Procurement Sources and Price Research Methods
The temporary auxiliary coins of the Showa 20s are relatively easy to acquire, but selecting appropriate routes for checking condition and authenticity is important. Recommended procurement sources include: first, specialty stores dealing in modern coins. Member stores of the Japan Numismatic Dealers Association are highly reliable and provide courteous explanations of quality. Second, specialized modern coin auctions. Wartime and occupation coins regularly appear in Japan's major ancient coin auctions. Third, coin shows or department store coin fairs. These are effective opportunities to inspect items firsthand. For price research, referring to databases of past auction winning records is effective. Domestically, the winning records of "Kosenkai" or "Tokyo Kotenka" are helpful. Internationally, sites like NumisBids that aggregate international auctions can search for Showa auxiliary coins from Japan. For an overall purchase guide, see Guide to Procurement Sources and Purchase Methods for Old Coins.