Kan'ei Tsūhō

The Kan'ei Tsūhō was cast in such enormous quantities—estimates suggest tens of billions—that it effectively standardized Japan's currency for over two centuries.

This copper coin, with its square hole and simple inscription, was produced using sand molds in various mints across Japan. Mintage figures vary by year and location, but records from the Edo period are spotty, with many lost to fires or wars. We know it was made from imported copper, sometimes recycled from foreign coins, which helped stabilize an economy in flux.

One odd detail: the coin's design barely changed over time, making counterfeits a persistent headache for officials. As for myths, I've heard tales of supernatural origins, but that's just nonsense peddled by overeager collectors. The reality is straightforward—it's a durable piece of everyday money.

Production halted in 1870 with the Meiji reforms, yet examples still turn up in hoards. Don't ask me why; some things just persist.