Sharpness Only Achievable by Artisans

Kurotori Forge began as a branch of the main Kurotori (Kawashima family), recognized as one of Tosa’s leading blacksmiths. In its early days, the forge mainly produced forestry blades essential to the local community, such as planting sickles and branch-cutting hatchets.

Blacksmiths who make agricultural, fishing, and daily tools are called "field blacksmiths (野鍛冶)," notable for crafting tools tailored in size and weight to the user’s needs. This forge continues this field-blacksmith approach, handling everything from production to maintenance.

"Drawing on the foundation of durability and sharpness in forestry blades, we’ve evolved as a field blacksmith by serving the requests of the local community. Today, we fulfill detailed requests such as adjusting the shape or balance of knives, creating practical blades tailored specifically to individual customer needs."

Since the COVID-19 pandemic, demand from inbound customers has risen, and some requests can even lead to a two-year wait.

While some machinery is used as needed, the majority of manufacturing is still done by hand. They forge about 50 pieces and perform heat treatment on about 200 per day, but due to the time-consuming process of heat treating and sharpening, only about 10 finished blades are completed each day.

When asked why they don’t mechanize further, Kajihara explained, "We wouldn’t be able to express our unique character."

"Mass-produced knives are punched out by presses, making the blade thickness uniform from tip to base, and because the metal is softer and less suited for sharpening, the edge doesn’t last. On the other hand, artisan-crafted knives become thinner toward the tip, and by fine-tuning the hardness through careful heat treatment, their sharpness lasts far longer."

Blades made by artisans offer a level of quality impossible for pressed knives. Of course, they’re more expensive than mass-produced alternatives, but their value more than justifies the cost.

What hasn’t changed over 150 years is the commitment to making knives that stand by the user. It's this spirit that continues to attract support today.

Materials, Shape, & Thickness—The Key to Sharpness

Knife-making at Kurotori Forge follows approximately seven steps: selecting materials, forging, rough grinding and shaping, heat treatment (annealing, quenching, tempering), water sharpening, blade honing, and attaching the handle. The secret behind their sharpness lies in the choice of steel and the blade’s shape and thickness.

"Depending on the object being cut, the blade angle that 'bites in' most smoothly varies. For instance, when cutting round objects, a slightly rounded tip better targets the center.

And regarding knives with a curve versus a straight edge—taller people tend to press down from above, making curved blades easier to use. In contrast, shorter individuals find straight blades more manageable."

For hunting, they design knives for ease of use closer to the ground, tailoring the curvature and angles based on the user’s height and working environment—evidence of the careful attention given to each blade produced at this forge.

"If a kitchen knife is too soft or too hard, it becomes difficult to sharpen and loses its edge. Achieving the ideal hardness makes precise heat treatment essential.

There are three key steps in the heat treatment process: 'Yaki-namashi,' which aligns the particles of metal stressed by forging; 'Yaki-ire,' to draw out the hardness of steel; and 'Yaki-modoshi,' where the blade is tempered in oil to balance hardness. These processes determine the performance of the blade."

In the finishing sharpening stage, invisible burrs ("Kaeri") along the edge are meticulously removed, and the thickness is carefully adjusted. This results in a smooth, clean cut sharp enough to slice through newspaper effortlessly. With a sharp knife, cutting onions won't crush the fibers, meaning you won’t experience the typical eye irritation. When slicing a cake topped with fruit, you can also achieve a clean cut without squashing the cake.

However, he recommends a wooden cutting board because the blade is quite delicate and a plastic cutting board tends to lose its sharpness.

The performance of knives varies depending on whether they are made by machine or handmade by craftsmen, but they also have characteristics unique to the region where they are produced.

"Metal tends to chip and break easily when cold, so it is often finished softer in colder regions, but the sharpness is reduced. Kochi has a relatively warm climate, so it can be finished hard. That is why it is reputed to have good sharpness."

A Lasting Connection With Our Customers

Kajihara is also involved in product development. When "batoning" (a technique for splitting wood with a knife) became popular among campers, he invented the "Butcher Knife," combining the strengths of both an axe and a deba knife.

"The idea to create the Butcher Knife came when batoning took off as a lifehack. I thought, 'If you try to split kindling with a knife meant for a different use, you’ll end up breaking the knife and ruining its edge.' So, from a bit of creative thinking, I made this item, which went on to win the 37th Kochi Prefecture Local Industry Encouragement Award."

Some blacksmiths specialize solely in manufacturing blades, but Kurotori Forge has long handled both production and direct sales. This allows them to gather more candid feedback from users. "When we receive negative feedback, we’re able to improve and create even better products. It’s a great way to hone our skills as artisans," he says.

"There are sometimes orders with a two-year wait. We simply don’t have enough craftspeople to keep up," says Kajihara. Even though the factory is training more apprentices, demand still outpaces production. Another challenge lies in pricing.

"There is a considerable price difference between the inexpensive kitchen knives sold at home centers and Tosa-Uchihamono, which are traditional crafts. Compared with mass-produced items, our products can seem expensive—but truly sharp blades last a long time, making them far more cost-effective in the long run."

To dispel misconceptions like these, they are ramping up their presence on social media platforms and through videos.

Looking to the future, Kajihara says, "I hope to expand the factory and increase production capacity so that we can deliver our products to customers more quickly." He adds that he has other ambitions as well.

"We’re building company housing now, but I’d love to open a guesthouse too. I want to give visitors a hands-on experience in forging blades. Even if our knives cut sharply, I hope to forge an unbreakable connection with our customers."

Blades are an essential item for everyday life. The sight of someone hammering away in pursuit of the answer to "what makes a truly great blade?" surely shines as a beacon for the future of traditional crafts.