The historic practice of ninjutsu is believed to have been developed by mountain families as a means of defense against invaders and attackers at the time of feudal Japan. It was mainly meant to ensure their survival in a time of violent political turmoil. Throughout history many different schools (ryū) have taught their unique versions of ninjutsu. Ninjutsu was banned in the 17th century, but lived on in underground circles. From that moment on they became associated in the public imagination with assassins and spies. Today some of the fundamentals of ninjutsu can be learned by attending classes or training camps specialized in ninja survival and self defense techniques.
Armed Fighting Techniques
An important component of ninjutsu was the mastery of weapons. Ninjas were very good at archery, and also used special swords (katana), spears (yari), sticks, kusari-gama (chain sickle), naginata, kaginawa (grapnel) or ordinary tools as a weapon. Typical of the Ninjas was that they carried their weapons concealed on their body or in their clothing. They were also very good at turning into weapons everyday objects such as a rope or rake that they could easily carry with them without arousing suspicion.
Shadow Weapons and other typical Ninja Weapons and Tools
The Ninja special weapon was the famous shuriken, a star-shaped weapon used for throwing, stabbing or slashing that was concealed in folds of clothing or tucked into sashes. Spike Shuriken could even be worn in the hair or a wig. These hand-held blades could be made from a variety of everyday items such as needles, nails, and knives, as well as coins and other flat plates of metal. Shuriken were usually used as a secondary weapon in a supportive function to the ninja's main.
Other weapons that were used because they could be easily concealed or carried without arousing suspicion were the Kunai (a trowel with a leaf-shaped blade that could be tied the body for concealment), Kumade (rake), Kyogetsu-shoge (a rope with a sharp hooked blade at one end and a heavy iron ring at the other that was sometimes preferred over a chain because it is a silent weapon and can be worn as a belt without arousing suspicion).
Typical Ninja weapons include the kusari-gama, a Japanese type of sickle attached at a metal chain, could be easily made and Nekode (climbing claws): a pair of straps or gloves fitted with spikes on the palm side that was used for a better grip when climbing walls or cliffs. While wearing nekode, a character can still wield other weapons without penalty. Nekode could also be used as a weapon. However, they were worn only when specifically needed, because they easily gave away the user as a ninja.
The typical ninja sword is the ninjato, a short sword that could be easily hidden on the body and could be used in close-combat due to its short range. It usually has secret compartments in the hilt of the sword or tip of the scabbard where blinding powders or poisons can be carried. The scabbard is generally open at both ends and can be used as a blowgun or snorkel. The silk cord wrapping that sometimes adorned the scabbard could be used for climbing when unwound.
The arsenal used by ninjas was often composed of everyday objects or natural elements that were easy to find. Ninja typically used bamboo, egg shells, nut shells, small bottles, and wooden boxes. Egg shells and nut shells could be used as containers for sight removers (Metsubushi) used to distract and blind attackers. Bamboo was used as guns or to build ambushes. Note that Metsubushi included more than just techniques to blind the eyes. Clouding the mind, for example using shadow technique (koei-no-jutsu), was considered another important way of blinding the eyes.
Unarmed Fighting Techniques
Stealth, Infiltration, Exfiltration, Sabotage and other Strategies and Tactics
The unarmed fighting techniques were based on various traditional Japanese close combat martial arts. These included techniques for breaking bones (Koppojutsu), pressure points and nerve points techniques (Koshijutsu) and rolling and falling (ukemi), as well as throws, joint locks, pins and striking patterns. These techniques are referred to as Taijutsu, which is not a martial art in itself, but rather a a generic term meaning 'body skills'.
Apart from traditional fighting techniques (armed and unarmed) their training also included training in disguise, impersonation and infiltration (Hensojutsu), stealth and entering methods (Shinobi-iri), escape and concealment (Intonjutsu), espionage and sabotage (Choho), pyrotechnics and explosives (Kayakujutsu), horsemanship (Bajutsu), strategies and tactics (Boryaku), geography (Chimon), meteorology (Tenmon), medicine, spiritual refinement (Seishin-teki kyoko).
An important part of the ninjutsu is dedicated to learning methods to attain invisibility in order to escape in infiltrate a situation or locus. Therefore, ninjas were taught techniques for silent movement and climbing and learned the art of concealing oneself using the five elements of earth, fire, water, wood, and metal (Gotonpo). Examples are fire evasion through smokescreens and tactical fires, earth evasion by burying oneself below the earth, wood evasion by running up trees or using various rope techniques, water evasion using water urns, wells, and rivers to hide and watch opponents, and metal evasion, using firearms or other metal weapons. They also learned how to distract guards and exploit their psychological weaknesses.
To facilitate infiltration ninjas also had to be able to learn the character traits of another class quickly and then impersonate the members of that class. A ninja typically had to appear either as a priest, samurai, merchant, craftsman, performer, puppeteer, or farmer. To accomplish this, the ninja was a well studied sociologist observing people in other towns for long periods of time until they could blend into the crowd. This form of ninjutsu was also known as "Shichi Ho De (七方出) or, "seven ways of going" as ninjas had to be able to imitate seven different classes of people or professions.
Ninja had to know how to survive in the most adverse conditions or environments. Apart from learning how to survive without leaving any trace of their presence they ninja would also have a sound knowledge of botany, entomology, geology, and zoology in order to determine their location, based on their natural surroundings (Chimon). They would also be able to find water in the most unlikely places, purify it, and transport it over long distances. Water was also used as a weapon, when they destroyed bridges, dikes, or contaminated water sources, or withheld water supply from a strategic point. The ninja training techniques involving water are called Suiren. In the same way ninjas could use meteorology as a strategic weapon (Tenmon). By foreseeing weather changes, analyzing animal behavior, or reading atmospheric signs, they could use natural events as a strategic advantage to weaken or surprise the enemy.