A lot of people think that Ninjas were once the James Bond of Japan.
According to professor Yuji Yamada, who is a leading scholar in Ninja, they were more like newspaper reporters and not considered nearly as glamorous as 007. Indeed, both the rank and salary of a Ninja was below that of a Samurai.
The word 'Ninja' didn't exist until the 1800s - long after real Ninjas existed. They were called Shinobi 忍 when they were actively hired by people called Daimyo 大名 (lords), who were vassals of Shogun during the Sengoku period.
An artist named Hokusai Katsushika gets credit for the first image of a ninja in the classic black suit that nowadays we envisage such a figure would have worn.
However, ninjas used to dress to suit whatever and wherever their missions were. Most dressed like a farmer so that they didn't get attention and could easily blend in.
Koga and Iga clan were famous for producing professional Shinobi, specifically trained for their roles. These professional Shinobi were hired as assassins and spies by daimyo between 1485 and 1581.
Shinobi studied not only the martial arts of Samurai and Bushido, but psychology as well in order to extract information from people.
Literature from Koga says that it is necessary to make all plans using the seven emotions of human beings: 'joy, anger, pathos, humour, love, hate and greed'.
An extract from Iga states, it is important to consider always the seven emotions of human beings. In order to develop a good relationship with people, it is necessary to act by knowing yourself and your limitations.
Later in history, Shinobi from Koga would become regarded as agents of the Tokugawa Bakufu (feudal Japanese military government), at a time when the Bakufu used the shinobi in an intelligence network to monitor regional daimyo as well as the imperial court.
There are not many written detailed documents about what shinobi did and achieved, as the whole point of shinobi was that their existence should not be recognised. Hence our image of shinobi became Ninja, which is the modern creation of a Japanese James Bond, propelled since the Hokusai manga.