Koshitaka (越孝) is a brand of professional-grade architectural chisels (nomi) handcrafted by master blacksmith Takagi Hikohachiro (高木彦八朗)in Sanjo City, Niigata Prefecture.

As one of Sanjo’s most prominent craftsmen, his work is highly regarded among professional carpenters and woodworkers for its exceptional quality and performance.

1. Traditional Craftsmanship

Koshitaka chisels are produced using traditional hand-forging techniques. Each piece is meticulously crafted, focusing on the critical processes of forge welding (tansetsu)—joining the hard steel to the soft iron base—and precise heat treatment. This results in a blade that offers a razor-sharp edge and remarkable durability (edge retention).

2. Premium Steel Selection

Nakai primarily uses Yasugi Steel, specifically White Paper Steel (Shirogami) or Blue Paper Steel (Aogami):

• White Paper Steel: Known for its purity and ease of sharpening. It achieves an incredibly fine edge, making it ideal for delicate finishing work.

• Blue Paper Steel: Contains chromium and tungsten for higher wear resistance. It is preferred for working with hardwoods or for tasks requiring long-lasting sharpness during heavy use.

3. Design and Variety

• Versatility: The lineup includes various types such as Oire Nomi (bench chisels) and Mukomachi Nomi (mortise chisels), catering to different professional needs.

• Finish: These tools are recognized for their beautiful Ura-dashi (the hollow-ground back) and overall balance. They are designed to feel like an extension of the hand, becoming more comfortable with years of use.

4. Reputation and Rarity

Sanjo City is world-renowned for its blacksmithing heritage, and Koshitaka is often cited as a prime example of the "functional beauty" found in high-end Japanese tools. Because they are handmade by a single master, the supply is limited, and they are increasingly considered rare items with high collector value.

These tools are favored by a wide range of professionals, from elite temple builders (Miya-daiku) to boutique furniture makers who demand the absolute best from their equipment.