People couldn’t tell who they were, or at least what their alter ego was. The wide range of skills practiced by ninja is called ninjutsu, the art of stealth, and includes training in armed combat, weapons techniques, military strategy, meteorology, geometry and respiratory synthesis. Ninjutsu has been passed on from generation to generation within families or directly from the teacher to one or a few selected disciples. This secret partly explains why there is little objective information about ninja, giving rise to many stereotypes inside and outside Japan. Ninja became a mercenary in the 15th century, where they were recruited as spies, attackers, arsonists and even terrorists.
In Kojiki, the young Yamato Takeru disguised himself as a charming young girl and murdered two leaders of the Kumaso people. However, these records take place at a very early stage in Japanese history and are unlikely to be linked to the shinobi of subsequent accounts. The first recorded use of espionage was used by Prince Shōtoku in the 6th century.
Therefore, the main unknown factor in the search for ninja is that an unknown number came from the Ashigaru and samurai class, and all that can be said is that the ninja came from both classes. Large areas of armies and fighters were based on the peasant class and remained under the banner of the infantrymen; however, some of these men were promoted and in fact helped shape Japanese history. In addition to this, some ninjutsu lines were contained in families and transmitted by the line or to a relevant candidate in the family, but family connection was not a requirement for shinobi training as is generally believed. Today, most people recognize the stealth killers represented in movies, TV shows and other forms of media such as ninjas.
According to Turnbull, ninja was trained from childhood, as was also common in samurai families. A distinction must be made between ninja in these areas and commoners or samurai hired as spies or mercenaries. Unlike their counterparts, the Iga and Kōga clans produced professional ninja, specially trained for their roles.
Known as ninjutsu, he teaches professionals the essential skills used by shinobi, including guerrilla warfare, espionage and infiltration. There is also the Bujinkan system which teaches unarmed and armed combat techniques in Ninjutsu. One of the school’s most prominent teachers, Stephen K. Hayes, since he retired from the rollers, is famous for publishing a series of “how to do” books on Ninjutsu. Although Bujinkan is not really derived from martial arts used by ninjas, since Ninjutsu is not a martial art, despite what many people think. Ninjutsu’s art consists of guerrilla and spy strategies; not direct combat techniques.
Basically was the genine (“lower person”), field agents from the lower class and assigned to real missions. During Sengoku Jidai, the most prolific Shinobi came from Koka or Koga Province and Iga Province, stiff clans and secrets known for guerrilla warfare, unorthodox tactics and the sale of these services to warlords. Their mysterious stories and their supposed rivalry have been popular fodder for Japanese fiction for years. Although it is commonly accepted that he is from Japan, ninjas can come from China, and the idea and practice then spread to Japan.
These professional ninja were actively hired by daimyō between 1485 and 1581, until Oda Nobunaga invaded the province of Iga and eliminated the organized clans. The survivors were forced to flee, some to the Kii Mountains, but others arrived before Tokugawa Ieyasu, Ninja where they were treated well. Some former members of the Iga clan, including Hattori Hanzō, will later serve as Tokugawa bodyguards. The ninja title has sometimes been retrospectively awarded to the semi-legendary prince of the 4th century Yamato Takeru.