Handcrafted replica of the Kōyō tanto samurai dagger, T-10 steel

Functional tanto Japan Swords Kōyō – T10, Shōbu-zukuri, Suguha hamon

Functional Kōyō tanto is a finely crafted replica of a traditional Japanese tanto with a sharp blade made of high-quality T10 carbon steel. Elegant shōbu-zukuri geometry, a genuine straight suguha hamon created by differential hardening and traditionally styled aikuchi koshirae form a harmonious combination of functionality and Japanese aesthetics. The blade reaches a hardness of approximately 58 HRC. The overall length of the tanto without saya is 50 cm, and the blade length including habaki is 33.3 cm. The name Kōyō (紅葉) refers to the autumn colouring of Japanese foliage. Muted shades of brown, a copper-coloured habaki, golden details, brown sageo and a dark glossy saya give the tanto an elegant appearance inspired by the colours of Japanese autumn.

#ShowMore#

At the heart of the Kōyō model is a sharp functional blade made of T10 carbon steel. T10 is suitable for manufacturing functional Japanese blades thanks to its high carbon content, ability to reach high hardness and very good edge retention.

In this tanto, quality steel is combined with differential heat treatment. The combination of correct geometry, material and hardening is among the most important factors influencing the properties of a Japanese blade.

You can find more about T10 steel and other materials used in the manufacture of Japanese blades in the article Katana blade – complete overview of steels, types and quality.

The blade is differentially hardened. The edge therefore achieves higher hardness, while the body of the blade retains greater toughness. On the Kōyō model, the edge hardness reaches approximately 58 HRC.

Another result of this type of heat treatment is a genuine hamon. It is not a decorative line created by grinding or etching, but a visible boundary formed during the hardening process.

You can find more about genuine hamon and differential hardening in the article Hamon in detail – how to recognise genuine katana hardening.

The blade features the traditional suguha (直刃) hamon. This type of hamon is characterised by a relatively straight line running parallel to the edge. It has a very clean, calm and elegant appearance and perfectly complements the character of this tanto.

On the Kōyō model, the suguha hamon is created by genuine differential hardening of the T10 carbon steel blade.

The blade geometry follows the shōbu-zukuri (菖蒲造) style. A typical feature is the smooth continuation of the main blade lines towards the tip without a pronounced transverse yokote, which in other construction types separates the kissaki.

The result is an elongated, slender and dynamic profile. The name shōbu refers to an iris leaf, whose elegant shape this geometry resembles.

You can find more about the construction and geometry of Japanese blades in the article Geometry and construction of a Japanese blade.

The Kōyō tanto is mounted in the aikuchi koshirae style. This mounting is characterised by a clean silhouette without a dominant classic tsuba and a visually smooth transition between the handle and the scabbard.

The aikuchi style is traditionally associated mainly with shorter Japanese blades, and on the Kōyō model it allows the geometry of the blade itself as well as the elegant craftsmanship of the tsuka and saya to stand out.

The tsuka handle is fitted with brown ito wrapping, creating a traditional crossed structure with regular diamond-shaped hishi openings. The firm wrapping is not only an aesthetic element but also contributes to a secure and stable grip.

You can find more about tsuka construction and the significance of the individual handle components in the articles Tsuka – the foundation of the katana handle and Ito – katana handle wrapping.

Beneath the wrapping, a light-coloured base in the style of traditional samegawa is visible. Traditionally, this term refers to ray skin used under the handle wrapping to increase the stability and strength of the construction.

Golden decorative menuki elements are set into the wrapping. They give the handle a more distinctive character, while their relief can also help improve hand orientation during the grip.

More information can be found in the articles Samegawa – traditional handle material and Menuki – decorative and functional detail.

The front part of the tsuka is finished with the fuchi, while the opposite end features the kashira. These elements help close and reinforce the handle construction and at the same time form an important part of the overall appearance of the koshirae.

More about their significance: Fuchi – handle collar and Kashira – handle end cap.

A distinctive detail is the habaki in a warm copper shade. The habaki surrounds the blade where it transitions into the scabbard and helps ensure its correct fit in the saya.

The dark glossy saya with light longitudinal lines creates an elegant contrast with the polished blade. The scabbard is complemented by a brown braided sageo attached in the kurigata area, matching the colour of the tsuka wrapping and visually unifying the entire set.

Tanto Kōyō combines a T10 carbon steel blade, genuine differential hardening, an edge hardness of approximately 58 HRC, a genuine suguha hamon and elegant shōbu-zukuri geometry. It is therefore not merely a decorative imitation, but a functional replica of a Japanese tanto.

Elegant aikuchi koshirae, brown ito, golden menuki, a copper-coloured habaki, dark saya and colour-coordinated sageo give this model a distinctive character inspired by Japanese autumn. Kōyō will appeal to collectors, lovers of Japanese history and customers looking for a genuinely sharp and technically interesting Japanese blade.