Ninja (忍者) were a type of warrior who specialized in unconventional warfare such as infiltration, sabotage and assassination during the age of the samurai. Another way of calling them is "shinobi", meaning "those who act in stealth". Ninja employed deception and forgery tactics to take opponents out by surprise. Due to their unorthodox methods which contradicted the way of the warrior (bushido), the ninja were not credited with the same honor as the samurai.
The diverse range of skills practiced by the ninja is called ninjutsu - the art of stealth - and includes training in armed combat, weapon techniques, military strategy, meteorology, geometry and breathing synthesis. Ninjutsu was passed down through generations within families or directly from teacher to a selected one or few disciples. This secrecy in part explains why little factual information exists about the ninja, giving rise to lots of stereotyping of them both within Japan and in the West.
As early as the 11th century, the inhabitants of Iga and Koka gained a reputation for their skills in unconventional warfare. Close to the political center Kyoto, yet distinctly remote due to their rugged terrains, Iga and Koka presented an ideal hideout location for refugees, bandits and losing parties of battles. Many ninja families lived here within autonomously governed communities, developing their martial skills for self defense.
During the age of the warring states in the 15th and 16th centuries, many warlords would hire the ninja of Iga and Koka as mercenaries for their set of unique skills in facilitating the conquest of castles and victories in battles. These were the heydays of the ninja.
Once peace was established in the 17th century, the ninja were mainly employed by the Tokugawa Shogunate to spy on the various regional lords and to guard Edo Castle. During these times, the ninja became greatly romanticized in popular culture, such as kabuki, which led to inaccuracies in the common perception of them. The stereotypes were subsequently exported to the West and further developed to entertain audiences there.
Where to appreciate the ninja today
The best places to appreciate the ninja today are Iga and Koka - the traditional heartlands of the ninja, and Togakushi in Nagano - home of the Togakure school of ninja. These respective regions offer some actual buildings used by the ninja in the past and/or museums which house previously used tools and weapons, thus retaining some level of authenticity.
Other ninja attractions include those found at theme parks and are relatively more commercialized. Ninja scenarios are recreated and ninja shows are staged according to popular conceptions for entertainment. Ninja mansions are a feature at many ninja locations. They are houses built with trapdoors and secret passages, forming mazes which visitors have to find their way through.
Several travel companies offer tour packages that allow participants to put on a samurai armor or ninja costume, learn about the various weapons and techniques, and in some cases take part in a mock battle. One of these companies, Japanican, offers several samurai and ninja tours.