Getting the point, to be blunt
If there is a ‘ninja sword’ is there a ‘ninja knife’? Well the closest that comes to it is the Kunai. Although to call it a knife would be a misnomer. The kunai was an entrenching tool, a climbing aid, rope anchor and many other practical tools before it was used for a weapon. Unlike the popularised Naruto and Manga imagery it wasn’t primarily a thrown weapon, although it could be thrown as a last resort. The literal translation of Kunai comes from the two parts it is made up of: Ku meaning death and nai meaning not to or negative. So the Kunai is meant to be used in a way that doesn’t take life, and the techniques reflect that premise. However it doesn’t mean you can’t break things with it.
It came in many sizes from small thin ones used to lever locks and pry small containers; to middle sized ones used to wedge doors, windows and used like pitons; to large ones used as rope anchors, digging tools and climbing aids. The design resembled a leaf or fish shape, and was made of iron. This made it a heavy tool. There were many different designs, depending on the use, but an average sized one would be about a 12 – 18 inches in overall length with a ring shaped pommel. The reasons for the ring shaped pommel was to make it easy to attach a rope (kunai fundo) or chain (kusarikunai) or to pass a bar through it to use it to bore holes in wood and plaster walls and floors. The blade itself was trowel shaped and the edge was blunt with a point and so wouldn’t cut, but could break and batter into structures. With its use as an entrenching tool the blade was thick to withstand the pressures of levering and digging, and the point sturdy rather than thin to reduce the chance of breakage.
The lack of a cutting edge is more of a benefit than many may think; after all it’s been said many times that there is nothing more useless or dangerous than a blunt knife. This is true if you need a knife. However if you use it for what it is, a blunt force trauma tool with a point, it excels in its function. In combat with a knife there is always the risk you will cut yourself with your own knife, as well as the opponent. There is then the risk of infection not only from dirt and other contaminants but also from any blood borne diseases that your opponent may have (not to mention that pesky DNA all over the place). With the kunai the risk of self-cutting is significantly reduced and almost eliminated. The risk of causing large blood loss in the opponent is also reduced. Blunt trauma to limbs, the head and torso will disable the opponent and facilitate an escape which is the ultimate goal in ninjutsu.
It is used as a hidden weapon and carried concealed to some extent. The idea being that most of the ninja’s equipment had to be carried easily on the body, so as not to impede the ability to run, climb, roll and generally move. Also when produced from a place of concealment the surprise factor would create openings and advantages in combat. Some of the more commonly used places for carry are inside the kyahan or the tekko, (leg and forearm wraps) and in the belt. With the lack of cutting edge it is quite safe to carry in these places and can be drawn while moving without being obvious. They also reinforce those areas to help deflect blows from edged weapons.
The stances (kamae) used are from Kukinshinden Ryu and the techniques that employ the kunai are a set of five called Juppo Sessho no waza. These can also be done with tessen, kodachi and other weapons as well as with no weapons. The five techniques are:
Kiri no Hito Ha
Each waza employs the either the flat or edge of the kunai to break grip or balance, and the point to pierce the opponents defence. It is usually shown against weapons (katana) but can be used against unarmed opponents as well.
The use of the kunai isn’t limited to these techniques, but they are more specific for it. It can be used in many other ways from wrist locks, strikes, chokes, throws (of the opponent) and so on. As with most things in the Bujinkan, the dynamics used in taijutsu (unarmed) techniques is reflected whenever a weapon is used with accommodation made for the characteristics of the weapon.
The kunai’s use as an entrenching tool usually meant it was needed for escaping through locked doors, windows and wall climbing so the ninja would try to hang on to it – literally! If, as a last resort, the kunai was thrown the weight and balance of the weapon (as well as its lack of cutting edge) would mean that it would most likely knock an opponent over, rather than stick in. If the ninja had to throw weapons they were more likely to use shuriken than kunai.