The History of the Ninja

It is said that the beginning of the ninja was the skill acquired by a mountain priest who went on a rough journey on Mount Togakushi around 678.
It is thought that the only person whose existence can be confirmed historically is a villain who resisted the power side’s rule in the latter half of the 13th century after the North and South dynasties (1336~92).
As a feature of the ninja, it was feared that the secret of the ninja would be passed to other people, and the record and the material were hardly left, and the exact figure is shrouded in fog as befits the ninja.
In the 940s, the founder of the Koga and Iga schools was a member of the Higashi Shinano clan.
He was defeated in the Battle of 1185 and escaped to Iga, where he added his own innovations to Iga-style ninjutsu and developed Togakushi-style ninjutsu.
The person who used the ninja the most during the Warring States period was Takeda Shingen. In addition to this, Ieyasu Tokugawa and Yukimura Sanada also have a lot of ninjas and have intelligence.
I put a covert operative on the case.
In the Edo period, the Iga and Kouga were called and held by the Tokugawa family to carry out activities such as security, observation of the construction site, and secrecy.
When the war in the Warring States period receded and the world became peaceful, ninjas did not use ninjutsu, but became apothecaries, farmers, doctors, merchants, and samurai.

Zhaoban Shimizu “Togakushi ninja” – Togakushi Nationalities Museum – Togakushi Zhaoban – “History of the ninja” – Kadokawa Sensho