In a nutshell ⚡
What is the Shinogi?
- The Shinogi is the ridge separating the cutting edge (ha) from the flat parts (Shinogi-ji) of a katana.
- It strengthens the blade by spreading the force of impact.
- High shinogi: strength for hard targets.
- Low Shinogi: fast cuts for soft targets.
- Shinogi-Ji: flat zone affecting speed and balance.
Or read on for detailed information 📚!
The Shinogi is the ridge that runs along the blade of a katana. This ridge separates the sharp, angular part of the blade, known as the Ha, from the flatter parts, known as the Hira or Shinogi-ji. The main role of the Shinogi is to reinforce the blade by distributing the force of impact during blows. This not only improves the sword’s strength, but also optimizes its cutting performance.
Shinogi varies according to the height at which it is placed on the blade. A higher crest line makes the blade more robust and suitable for hard targets, but it can make cutting softer targets less fluid. Conversely, a lower Shinogi can facilitate fast, precise cuts on soft targets, while making the blade more delicate to shocks.
Finally, a well-defined, straight Shinogi is often seen as a sign of swordsmanship excellence. Katana polishers pay particular attention to this line, as it highlights the blade’s unique structure and brings out the Hamon, the hardening line that emphasizes the cutting edge.
Shinogi-Ji
The Shinogi-Ji is the flat part of the blade between the Shinogi and the Mune. Although it may seem simple at first glance, the polish and finesse of the Shinogi-Ji influence the speed and balance of the blade when cutting.
The Shinogi-Ji is often polished to accentuate the blade’s shine. This smooth, carefully worked area also creates minimal air resistance, making the sword’s movements faster and more precise.
Role of Shinogi in Katana Performance
Shinogi and Shinogi-Ji directly influence how the katana performs in battle. A well-placed and correctly shaped Shinogi absorbs shock during parries and powerful blows while ensuring suppleness during fluid cuts. It acts as a natural shock absorber, distributing force throughout the length of the blade.
In terms of handling, a katana with a high Shinogi will tend to be stiffer, which is ideal for tackling more resistant targets. On the other hand, a lower Shinogi will make the blade thinner and more flexible, enabling faster, more precise attacks.
The area of the blade from the Shinogi to the cutting edge can contain more or less Hira-Niku (thickness), influencing strength and cutting ability. A blade with a lot of Niku is more resistant and cuts heavy targets better, while a blade with less Niku is sharper but more fragile.
Blades without Shinogi are called Hira-Zukuri and are very sharp for light targets, but vulnerable to harder ones. Most mass-produced katanas have a low crest line and little Niku, making them effective for light targets, but less durable.
The most common type of katana is the Shinogi-Zukuri, which combines a ridgeline and Niku, optimizing the blade for cutting heavy targets while resisting damage.
Balance between Shinogi and Bo-Hi
Another important factor to consider is the presence or absence of the Bo-Hi, a long line that often runs parallel to the Shinogi. The Bo-Hi lightens the blade while maintaining its solidity, enabling the swordsman to execute faster movements with less effort. When properly balanced with the Shinogi, the bo-hi offers the perfect combination of lightness and structural strength; in particular, in katanas with a bo-hi, the lighter weight offered by this groove maximizes cutting speed without compromising blade strength. A well-designed katana, with a well-proportioned Bo-Hi and optimized Shinogi, is capable of adapting to a variety of fighting styles and situations.