Nittoho Tatara, located in Okuizumo Town, Shimane Prefecture, is the only full-scale facility in Japan where the traditional ironmaking technique known as tatara ironmaking continues to be practiced. The facility produces tamahagane, a high-quality steel essential for making Japanese swords, and plays an important role in preserving Japan’s traditional sword-making culture.
The Okuizumo region has long been known for its abundant supplies of high-quality iron sand. Surrounded by mountains and rich forests, the area developed a distinctive ironmaking culture over many centuries. Even today, the traditional fire of tatara continues to burn at Nittoho Tatara, carrying this remarkable heritage into the modern era.
Tamahagane is a special type of steel traditionally used to create Japanese swords. It is produced through an ancient method called tatara-buki, a traditional smelting process that cannot be reproduced in the same way using modern industrial steelmaking.
Iron sand and charcoal are slowly refined inside a clay furnace. Because the process uses relatively low temperatures compared with modern blast furnaces, the resulting iron contains very little of certain impurities and can develop a combination of strength and flexibility.
These characteristics are essential to the distinctive qualities of Japanese swords, including their sharp edges and beautiful hamon, the visible patterns along the hardened edge of the blade.
Since the Edo period, tamahagane has been regarded as an essential material for Japanese swordmaking. Generations of swordsmiths have used it to create finely crafted blades, and even today, much of the steel used by contemporary Japanese swordsmiths comes from Nittoho Tatara.
Tatara ironmaking was once practiced in many parts of Japan. However, from the Meiji period onward, Western-style steelmaking technology began to spread. Modern steel mills could produce iron and steel on a much larger scale, causing traditional tatara ironmaking to decline rapidly.
Commercial tatara operations came to an end in the 1920s, and the traditional fires that had burned for centuries were extinguished. In 1933, Yasukuni Tatara resumed operations to produce tamahagane for military swords, but production was halted again after World War II.
After the war, Japanese swords came to be appreciated internationally as works of art. However, only a few tons of tamahagane remained in storage. Concern over the loss of this essential material led the Nihon Bijutsu Token Hozon Kyokai, or Society for Preservation of Japanese Art Swords, to begin efforts to restore traditional tatara ironmaking.
In 1977, Nittoho Tatara was established in Okuizumo Town by restoring the techniques once used at Yasukuni Tatara. After more than 30 years without a continuous tatara fire, the traditional flame was brought back to life in Okuizumo.
Tatara ironmaking is a distinctive Japanese ironmaking technique that developed over many centuries. Instead of using iron ore as the primary raw material, it mainly uses iron sand, which is mixed with charcoal and heated inside a clay furnace for an extended period.
The word tatara is believed to be associated with the bellows used to force air into the furnace. By supplying a powerful flow of air, the temperature inside the furnace can be raised sufficiently to extract iron from the sand.
Unlike modern blast-furnace steelmaking, tatara ironmaking operates at comparatively low temperatures. This helps reduce certain impurities such as phosphorus and sulfur and allows high-quality iron and steel to be produced through a carefully controlled traditional process.
A traditional tatara furnace is a low, rectangular structure made from clay. Bellows are installed on both sides to supply air and intensify the combustion of charcoal.
Inside the furnace, heat from the charcoal and carbon monoxide trigger reduction reactions that extract iron from the iron sand. Carbon is then absorbed into the iron in controlled amounts, producing steel that includes tamahagane.
Another distinctive feature is that the furnace is broken apart after each complete operation and rebuilt for the next one. This entire production cycle is known as a hitoyo.
Tatara ironmaking requires an extraordinary level of experience and intuition. The person responsible for overseeing the entire operation is known as the murage, or master tatara technician.
The murage carefully observes the color of the flames, the sound of the furnace, and changes in its condition. Based on these subtle signs, the murage adjusts the quantities of iron sand and charcoal as well as the airflow from the bellows.
Long before thermometers, digital sensors, and automated controls existed, this knowledge was passed down through generations. It represents a world of craftsmanship in which the senses and experience of the master play a crucial role.
Akira Kihara, who served for many years as a murage at Nittoho Tatara, is also known as a holder of a nationally designated conservation technique and made an important contribution to the transmission of traditional tatara technology.
A full tatara operation lasts approximately 70 hours continuously, day and night. The process is divided into several stages, including komori, nobori, and kudari, while iron sand and charcoal are repeatedly added to the furnace.
During the first stage, charcoal and iron sand are added to stabilize the furnace temperature. A substance known as noro, or iron slag, forms inside the furnace and helps retain heat.
Once the furnace reaches a sufficiently high temperature, masago iron sand, the main raw material for tamahagane, is added. At this stage, the flames gradually take on a golden-yellow color, while a large mass of iron called kera begins to form at the bottom of the furnace.
During the final stage, the amount of material added to the furnace increases and the kera continues to grow. When erosion of the furnace walls reaches its limit, the air supply is stopped.
The furnace is then broken apart so that the massive iron block inside can be removed. From this large mass, only the portions with the appropriate quality are carefully selected for use as tamahagane.
Okuizumo is home to numerous historical sites, cultural traditions, and landscapes associated with tatara ironmaking. In 2016, the region was recognized as part of the Japan Heritage story “Izumo-no-Kuni Tatara Fudoki: A Story Born from a Thousand Years of Ironmaking.”
The entire region can be viewed as a living historical landscape that preserves the cultural heritage created by Japan’s traditional iron industry.
The Okuizumo Tatara and Sword Museum introduces the history of tatara ironmaking and Japanese swords. Exhibits explain the production of tamahagane and the development of swordmaking, making the museum accessible even to visitors who are new to Japanese sword culture.
Sugaya Tatara Village is a valuable historical site preserving a tatara ironmaking settlement from the Edo period. The takadono furnace building, workshops, and residences remain, allowing visitors to imagine the lives of the iron masters and workers who once lived here.
These museums introduce the history of former ironmaster families who became prosperous through tatara ironmaking. Their grand traditional residences and beautiful gardens provide an insight into the wealth and social influence created by the iron industry.
Tatara ironmaking contributed to much more than Japanese sword production. The iron it produced was used for a wide range of industries and everyday objects throughout Japanese history.
During the Warring States period, high-quality iron supported the production of firearms and weapons. Iron was also widely used for agricultural tools and household items.
In the Chugoku Mountains, the transportation of iron sand and charcoal also encouraged improvements in working cattle and horses. This development is thought to have contributed to the later growth of Japan’s distinctive Wagyu cattle culture.
In Hiroshima, techniques associated with needle production developed from the tatara iron industry are also said to have contributed to technological developments that later influenced the origins of modern sporting-goods manufacturers such as Molten and Mikasa.
Today, Nittoho Tatara operates several times a year, producing tamahagane for Japanese swordsmiths throughout Japan. Each operation is much more than a process for producing steel. It is an important effort to preserve and pass on a unique part of Japanese cultural heritage.
In recent years, smaller-scale tatara demonstrations and hands-on activities have also been organized in various regions as part of local revitalization and educational programs. These efforts help introduce younger generations to the knowledge and craftsmanship behind traditional ironmaking.
A visit to Okuizumo offers an opportunity to experience a side of Japanese culture that cannot be found simply by visiting famous tourist attractions. The region reveals the deep relationship between nature, craftsmanship, industry, and traditional culture.
The tamahagane created from iron sand and charcoal in the intense heat of the tatara furnace represents centuries of accumulated knowledge and craftsmanship. At Nittoho Tatara, visitors can discover how this remarkable tradition continues to support the art of Japanese swordmaking today.