Himeji City in Hyogo Prefecture is home to Himeji Castle, a national treasure and UNESCO World Heritage Site. The region is also one of Japan’s leading leather-producing areas, where Tsuchiya Kaban’s signature Soft Nume Leather is crafted.

At Kinshun Leather Factory, located along the Ichikawa River, unfinished vegetable-tanned leather—known as “crust”—is carefully processed through techniques such as fatliquoring, dyeing, and texturing. Tanned solely with plant-based tannins, the leather retains its natural texture and character.

“Soft Nume Leather requires only the highest-quality crust leather,” explains Production Manager Kobayashi. “Our tannery craftsmen assess each hide individually by wetting the surface.”

Moistening the leather makes scratches and stains—often difficult to detect when dry—clearly visible. Only crust leather carefully selected by experienced craftsmen meets the standard for use.

One defining characteristic of our Soft Nume Leather is its distinctive texture and exceptional softness, which offers a remarkably comfortable feel in the hand or when worn over the shoulder. These qualities are achieved through an intensive oiling process—using nearly three times the amount of oil found in typical leathers. How, then, is such a generous quantity of oil infused into the leather?

“We place the crust leather into a large rotating drum with an ample amount of vegetable oil, along with water and aniline dye. As the drum turns, the oil and dye penetrate the leather simultaneously—the oil softening the fibers and enhancing suppleness through constant agitation. The oil ratio and water temperature are carefully adjusted for each batch to achieve a well-balanced finish that is not only soft, but firm and resilient.”

The subtle variations in the leather grain are also a charming characteristic of our Soft Nume Leather. Unlike embossing, which is a process of applying pressure to create a motif or pattern, leather grain is formed naturally, preserving the individual characteristics of each piece of leather.

“The textured grain is created through a process called dry tumbling, where the leather alone is placed in a rotating drum to form delicate wrinkle patterns. Several dowels inside the drum cause the leather to catch and fall repeatedly as it turns, producing the characteristic texture. In addition, the dry tumbling process further enhances the leather’s softness.”

Finally, the leather is inspected one last time before dye and oil are applied to the surface. This is where the spray machine comes into play. As the leather passes through, a rotating spray evenly coats it with dye and oil, ensuring thorough absorption. The process is repeated twice, with machine settings carefully adjusted each time based on the leather’s condition and the day’s weather.

“It has a rich, well-nourished feel without ever feeling oily. Achieving this delicate balance requires constant micro-adjustments—from the oil and dye mixture to water temperature and machine settings—a task that is incredibly demanding and depends largely on the discernment of an experienced craftsperson.”

Kinshun Leather Factory, the producer of our Soft Nume Leather, is a long-established tannery with a heritage in crafting himekawa—a type of white-tanned leather renowned in the region.

In recent years, the company has stepped up its environmental efforts—conserving water during the tanning process, carefully managing wastewater containing chemical substances, and switching from oil to gas fuel to reduce CO₂ emissions. They also maintain high traceability by sourcing domestic raw hides from trusted processors. Employee well-being is a priority as well, with investments in safer machinery and improved working conditions.

Himeji City, home to the tannery, recognizes leather as a traditional local industry and works closely with both public and private partners to protect the environment. To address the industry’s biggest challenge—wastewater treatment—the city has established a dedicated sewage system and pre-treatment plant for leather businesses. As a result, rivers once polluted by wastewater have become clear again, and water quality has improved significantly. This forward-thinking approach is helping sustain Himeji’s heritage leather industry while protecting the environment.

While it requires more care and effort to craft than typical leathers, Oil Nume Leather was developed to embody the essence of Tsuchiya Kaban—allowing people to fully experience the beauty, richness, and joy of leather.

A big part of this lies in the unique character of each piece of leather—shaped by the individual qualities of the animal and the specific part of the hide, as well as the way its color, luster, and texture evolve with use. Soft

Nume Leather is also versatile, lending itself to everything from structured, box-shaped bags to softer, more fluid silhouettes. Our goal was to create pieces that celebrate the natural beauty of leather—timeless designs to be cherished by people of all genders, generations, and styles.

We shared our vision with Kinshun Leather Factory, and after countless tests, the leather of our dreams was born. Yet the bag makers initially struggled with it due to its exceptional softness. Richly infused with oil, the leather behaved differently from other leathers, requiring further trial and error—including experimenting with core materials and construction techniques—before they mastered the appropriate approach to this extraordinary new material.

Thus, the “ideal leather bag” we had long envisioned was born—featuring a distinctive natural grain, rich texture, and exquisite softness. The Tone Nume Collection, now a signature series for Tsuchiya Kaban, embodies our commitment to authentic craftsmanship and creating pieces that are cherished across generations. It continues to evolve, with updated construction and designs that reflect the times, while staying true to its enduring values.