Nagato Coin Mint Site

Nagato Mint Ruins: Japan's Oldest Confirmed Coin-Minting Site

Hidden within the tranquil grounds of Kakuon-ji Temple in the historic castle town of Chofu, Shimonoseki, the Nagato Mint Ruins (長門鋳銭所跡, Nagato Juzenjo Ato) preserve the memory of an extraordinary chapter in Japanese economic history. This is the only archaeologically confirmed site in Japan where the legendary Wadōkaichin — the nation's first widely circulated copper currency — was produced over 1,300 years ago.

Designated as a National Historic Site in 1929, these ruins offer visitors a rare opportunity to stand on the very ground where ancient craftsmen once fired their furnaces and cast the coins that helped shape the economic foundations of the Japanese state during the Nara and Heian periods.

The Dawn of Japanese Currency

In the early 8th century, inspired by the monetary systems of Tang Dynasty China, the Japanese imperial court embarked on an ambitious program to introduce copper coinage across the nation. In 708, under the reign of Empress Genmei, the government ordered the minting of Wadōkaichin (和同開珎) — round bronze coins with a distinctive square hole in the center, modeled after the Chinese Kaigen Tsūhō coins first minted in Chang'an in 621 CE.

To supply the young nation with currency, the central government established official mints, known as jusenjo (鋳銭所), in several provinces including Ōmi, Yamashiro, Kawachi, Musashi, and Nagato. Among all these historic minting locations, only the Nagato Mint has yielded confirmed archaeological remains — making it an irreplaceable treasure for understanding early Japanese monetary history.

Why Was the Nagato Mint Located Here?

The choice of Nagato Province (present-day western Yamaguchi Prefecture) as a mint location was no accident. The region was rich in copper, the essential raw material for coin production. According to the Shoku Nihongi (Chronicles of Japan, Continued), copper mined at two locations in neighboring Suō Province — Ushijima Nishisu in Kumage District and Kiriyama in Yoshiki District — was sent to Nagato specifically for coin minting.

Furthermore, the famous Naganobori Copper Mine in what is now Mitō, Yamaguchi Prefecture — the very mine that supplied copper for the construction of the Great Buddha at Tōdai-ji Temple in Nara — also sent copper to the Nagato Mint. Wooden tablets (mokkan) discovered at the Naganobori mine confirm that copper was dispatched to both the Nagato provincial governor and the mint supervisor, providing compelling evidence of the extensive supply network that supported coin production here.

The mint was attached to the Nagato Provincial Government Office (国衙, kokuга), and the provincial governor held the concurrent title of Jusenji (Mint Supervisor), reflecting the critical importance of currency production to the central administration.

Archaeological Discoveries

The connection between this site and ancient coin minting had been suspected for centuries. As early as the Kan'ei era (1624–1644), molds for Wadōkaichin coins were discovered in the area. However, it was a systematic excavation in 1911, led by the temple's head priest, Reverend Shindō Tandō, that produced the breakthrough discovery of approximately one hundred minting-related artifacts, including coin molds (senban), bellows mouths (fuigo haguchi), and crucibles (rutsubo) for melting copper.

Subsequent excavations in the Taishō era yielded even more artifacts, leading to the site's designation as a National Historic Site in 1929. The excavated artifacts received designation as Important Cultural Properties in 1964 under the collective title "Nagato Province Mint Artifacts" (長門国鋳銭遺物), and are now preserved at the Shimonoseki City Museum of History (formerly the Chofu Museum).

Historical Significance

The Nagato Mint operated from the Wadō era (708–715) through approximately the early Tenpyō era (729–749), before being closed around 825 when its functions were transferred to the newly established Suō Mint (周防鋳銭司) in what is now Yamaguchi City. During its roughly 100 years of operation, the mint played a vital role in producing the currency needed to build and sustain the young Japanese centralized state.

What makes the Nagato Mint uniquely valuable is its status as the only confirmed archaeological site among all the locations known to have produced Wadōkaichin coins. While literary sources mention mints in provinces such as Ōmi, Yamashiro, Kawachi, and Musashi, no physical remains of those minting operations have been definitively identified. The Nagato Mint Ruins therefore stand alone as tangible evidence of Japan's earliest large-scale currency production — an achievement that cannot be overstated for scholars of Japanese economic and administrative history.

Visiting the Site: Kakuon-ji Temple

Today, the Nagato Mint Ruins lie within and around the grounds of Kakuon-ji Temple (覚苑寺), a Ōbaku Zen temple founded in 1698 by Mōri Tsunamoto, the third lord of the Chōfu Domain. The temple itself is a beautiful place of worship that serves as one of the family temples of the Chōfu Mōri clan, with several Mōri lords interred in its grounds.

Visitors will find a stone monument inscribed "Historic Site: Nagato Mint Ruins" (史蹟 長門鋳錢所阯) along with informational plaques explaining the site's significance. While the actual archaeological remains are preserved underground, the setting within the serene temple grounds provides a contemplative atmosphere perfectly suited to reflecting on the deep history beneath your feet.

Seasonal Beauty

Kakuon-ji Temple is renowned as one of Chōfu's finest spots for seasonal scenery. In late February and early March, approximately 50 plum trees bloom in shades of pink and white, signaling the arrival of spring. The temple grounds are also celebrated as one of the area's best autumn leaf viewing destinations, with around 100 Japanese maple trees creating a breathtaking canopy of crimson and gold. A magnificent ginkgo tree adds brilliant yellow to the autumn palette, and the carpet of fallen leaves that covers the temple grounds creates an unforgettable scene.

Every Sunday morning, the temple holds a Zen meditation (zazen) session, offering visitors a chance to experience the contemplative traditions of Ōbaku Zen Buddhism in an atmosphere steeped in over a millennium of history.

Exploring the Castle Town of Chōfu

The Nagato Mint Ruins are situated within the broader historic district of Chōfu, one of western Japan's most atmospheric castle towns. Once the seat of the Chōfu Mōri clan, the district retains its Edo-period character with earthen walls, traditional gates, and narrow lanes that transport visitors back in time.

Nearby attractions within easy walking distance include:

• Kōzan-ji Temple — A Kamakura-era Zen temple featuring a National Treasure Buddhist hall and a statue of Takasugi Shinsaku, the samurai who helped spark the Meiji Restoration
• Chōfu Mōri Residence — The elegant Meiji-era mansion of the Mōri family with three beautiful traditional gardens
• Nogi Shrine — Dedicated to General Nogi Maresuke, with a charming approach lined with stone lanterns
• Shimonoseki City Museum of History — Houses the excavated mint artifacts designated as Important Cultural Properties, along with extensive collections related to the Meiji Restoration and samurai history
• Furue-kōji Lane — A picturesque lane lined with traditional earthen walls that epitomizes the castle town atmosphere
• Iminomiya Shrine — An ancient shrine with connections to Emperor Chūai and Empress Jingū, hosting the lively Suitengu Festival

Practical Tips for International Visitors

The castle town of Chōfu is compact enough to explore on foot, and combining the Nagato Mint Ruins with other nearby attractions makes for a rewarding half-day or full-day excursion. The area is less frequented by international tourists compared to more famous destinations, offering an authentic and unhurried experience of Japanese history and culture.

Signage at the site is primarily in Japanese, so having a basic understanding of the site's history before your visit (or using a translation app) will greatly enhance your experience. The excavated mint artifacts at the Shimonoseki City Museum of History provide essential context and are highly recommended as a complement to visiting the ruins themselves.