You’re rummaging through a junk drawer or maybe a jar of "vacation leftovers" and you find it. It’s a round, metallic disc. It’s got a hole right through the center—or maybe it doesn’t—and it’s covered in those intricate, blocky strokes known as kanji. If you’re like most people, your first instinct is to grab some lemon juice or metal polish to see what’s underneath the grime.
Stop. Just don’t.
That Japanese coin isn't just pocket change; it's a tiny, metallic record of history that behaves very differently from the quarters and dimes you’re used to. Whether you're holding a 5-yen piece you got at a shrine in Kyoto or a silver 100-yen coin from the 1960s, these objects have a specific etiquette and value profile that most Westerners completely miss.
The Mystery of the Hole and the Kanji
Why do some have holes? Honestly, it’s mostly about saving metal and making them easy to identify by touch. The 5-yen and 50-yen coins are the ones with the center cutout. If you look at a 5-yen coin (go-en), you’ll see the kanji 五円. The "five" is the horizontal line with a little hat and legs. This coin is arguably the most famous round piece of metal in Japan because of a linguistic pun. Go-en sounds exactly like the word for "honorary connection" or "fate." That’s why you see people tossing them into offering boxes at temples. It’s not just money; it’s a prayer for a good relationship.
The metal matters too. A 5-yen coin is brass. A 10-yen coin is 95% copper. This is why your 10-yen coins often look like a dirty penny that’s seen better days. But if you find one with "reeding"—those little ridges on the edge—you might have a "Giza 10." These were minted between 1951 and 1958. They’re relatively rare. Most 10-yen coins today have smooth edges. Collectors hunt for the Giza-ju because it represents a specific era of post-war Japanese recovery.
Reading the Date (It's Not What You Think)
You won’t find "2024" or "2026" on these coins. At least, not in the way you expect. Japan uses the regnal calendar. This means the year is tied to the reign of the Emperor. Currently, we are in the Reiwa era.
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If you see the kanji 令和, that’s Reiwa. Before that was 平成 (Heisei, 1989–2019), and before that was 昭和 (Showa, 1926–1989). To find the year, you look for the era name followed by a number and the kanji for year (年). So, "Reiwa 6" is 2024. It’s a bit of a math puzzle every time you look at your wallet.
The Collector's Curse: Why Cleaning Kills Value
Here is the thing about Japanese coins that trips up everyone: the "patina."
Serious numismatists—that’s the fancy word for coin nerds—hate shiny coins. Well, they hate artificially shiny coins. When you use an abrasive cleaner on a copper 10-yen coin, you’re stripping away a layer of oxidized metal that took decades to form. To a pro, a cleaned coin is a damaged coin. It looks "harsh." The value can drop by 90% the second the vinegar touches the metal.
Think about the 1-yen coin. It’s made of 100% aluminum. It’s so light it can actually float on water if you place it carefully. Because it’s so soft, it scratches if you even look at it funny. If you find an old aluminum coin with a beautiful, matte grey finish, leave it alone. That dullness is its armor.
Spotting the Silver: The 100-Yen Secret
Most people assume all modern coins are just "pot metal"—zinc, nickel, and copper blends. Usually, they're right. But if you go back to the mid-20th century, Japan was still putting real silver in their circulating currency.
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Between 1957 and 1966, the 100-yen coin was a beautiful silver piece. The early ones featured a phoenix; the later ones showed a rice ear. If you find a round metallic coin with 百円 (100 yen) and it feels a bit heavier or sounds "ringier" when dropped on a table, check the date. If it’s from the Showa era (昭和) years 32 through 41, you’re holding 60% silver.
Modern 100-yen coins are cupronickel. They’re fine. They buy you a canned coffee at a vending machine. But those silver ones? They’re a hedge against inflation sitting in your palm.
The Cultural Weight of a Round Piece of Metal
In the West, money is just money. In Japan, these coins are often treated with a level of respect that feels almost spiritual. You’ll notice store clerks take your coins in a small tray (suruton) rather than grabbing them from your hand.
This brings us to the 500-yen coin. It’s one of the highest-value circulating coins in the world. It’s big, gold-colored (nickel-brass), and hefty. If you have the newer version (issued around 2021), it’s actually "bimetallic"—it has a different colored ring around the center to prevent counterfeiting. When you see 五百円 on a coin, treat it like a $5 bill. Don't just toss it in a jar.
Misconceptions About Rarity
I hear it all the time: "I found a coin from the 40th year of Showa! It must be worth thousands!"
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Probably not.
Japan minted millions upon millions of these. Rarity usually comes from "error coins." Look for:
- Off-center strikes: Where the design isn't centered on the round disc.
- Missing holes: A 50-yen coin that didn't get its center punched out is a holy grail for collectors.
- Clogged dies: Where the kanji looks blurry or filled in because the machinery was dirty.
How to Handle Your Find
If you have a Japanese coin and you’re curious about its history, your first step is identification. Look for the era kanji first.
- Identify the Era: Is it 昭和 (Showa), 平成 (Heisei), or 令和 (Reiwa)?
- Check the Metal: Is it lightweight (aluminum), reddish (copper), or yellowish (brass)?
- Find the Denomination: * 一 = 1
- 五 = 5
- 十 = 10
- 五十 = 50
- 百 = 100
- 五百 = 500
Once you know what you have, store it in a PVC-free plastic flip. PVC can actually "weep" onto the coin and create a green, slimy residue that eats the metal. It’s called "green slime" in the hobby, and it’s a nightmare to fix.
Actionable Steps for Your Metallic Treasure
- Audit your collection: Sort them by the era names listed above. Use a magnifying glass to look at the edges.
- Avoid the "Bright Idea": Never use baking soda, toothpaste, or jewelry cleaner. If the coin is truly filthy with dirt (not oxidation), a 24-hour soak in pure acetone (not nail polish remover, which has oils) is the only "expert-approved" way to remove organic gunk without hurting the metal.
- Check the "Giza" factor: Look at your 10-yen coins. If the edge has ridges, it’s a 1950s relic. Keep it separate.
- Verify Silver Content: Use a kitchen scale. A silver 100-yen coin (1959-1966) should weigh exactly 4.8 grams. A modern cupronickel one is exactly 4.8 grams too, so you actually have to rely on the date or a magnet—silver isn't magnetic, but some nickel alloys are. (Wait, actually, both aren't strongly magnetic, so the date 昭和 is your best bet).
- Market Research: Use sites like Numista to look up mintage numbers. If the mintage for that specific year was under 10 million, you might have something worth more than its face value.
Understanding these coins is basically a crash course in Japanese history and linguistics. They aren't just currency; they are artifacts you can carry in your pocket. Treat the metal with respect, keep the kanji legible, and whatever you do, leave the polish in the cupboard.