During the Sengoku period of japan, while the samurai were fighting over land for their employers, certain clans had begun employing mercenary agents to, among other things, sabotage, assassinate and infiltrate high value targets. The equivalent of modern day special ops soldiers, the Ninja fought in ways that were contrary to the traditional honor driven strictness of the samurai. The diverse range of skills they were trained to use was call Ninjutsu - the art of stealth - which taught armed combat, weapon techniques, military strategy, meteorology, geometry and controlled breathing.
The tasks the Ninjas were given were not of usual military practice. often small groups of ninja were given assignments involving infiltration behind enemy lines, to spy on commanders and gain intelligence on what their plans were. Arson was another tactic used by the ninja to achieve dominance for their employers. On one occasion a group of 48 ninja entered an enemy castle by replicating the uniforms worn by officials in order to set fire to it from the inside. The 48 ninja emerged without harm and their employers were able to successfully invade and take over the territory. Being trained in the arts of stealth, the ninja were perfect candidates for assignments involving assassinations. Although the most famous accounts were failed assassinations, many were successful, as the ninja used extremely unorthodox methods such as hiding weapons underneath floorboards or waiting in bathrooms for their victims.
The ninja were generally disguised as civilians, but were known to wear outfits made of black cloth that was tinted red to hide bloodstains. They were also known to use lighter variations of samurai armor. The tools the ninjas used during their operations were numerous.ropes and grappling hooks were commonly used to scale walls and enter the compounds of important buildings. spikes attached to their boots and gloves were also sometimes incorporated for this purpose. Sharp tools were used for gouging holes in the walls of building to gain access to them or create footholds for climbing, and were usually attached the Ninja's belt. The weapons used by ninja were often times normal tools used for gardening such as sickles or sharp shovels, so that if the ninja was discovered, he could claim they were his tools for working. The Katana was used extensively by the ninja, as well as short bows, various types of throwing blades, and at later times explosive devices that would release poison or send shrapnel through the air.
http://www.japan-guide.com/e/e2295.html
http://asianhistory.about.com/od/warsinasia/p/NinjaProfile.htm
The ninja were generally disguised as civilians, but were known to wear outfits made of black cloth that was tinted red to hide bloodstains. They were also known to use lighter variations of samurai armor. The tools the ninjas used during their operations were numerous.ropes and grappling hooks were commonly used to scale walls and enter the compounds of important buildings. spikes attached to their boots and gloves were also sometimes incorporated for this purpose. Sharp tools were used for gouging holes in the walls of building to gain access to them or create footholds for climbing, and were usually attached the Ninja's belt. The weapons used by ninja were often times normal tools used for gardening such as sickles or sharp shovels, so that if the ninja was discovered, he could claim they were his tools for working. The Katana was used extensively by the ninja, as well as short bows, various types of throwing blades, and at later times explosive devices that would release poison or send shrapnel through the air.