Ninjas have historically been called “Shinobi” and are believed to have existed since the Northern and Southern Dynasties.
The origin of the ninja is believed to be those who resisted the rule of the manor system in the latter half of the 13th century.
During the Warring States period, Shinobi was called by daimyo in various places to invade enemy nations, ambush, and collect information.
The image of our ninja is people hiding in the attic and eavesdropping on conversations. However, it seems that the actual ninja got along with the people in each area and asked for information.
In the 17th century, ninjutsu books were written that described Shinobi’s methods and attitudes. There were various descriptions such as dialogue, mnemonic, communication, magic, medicine, pharmacy, food, astronomical, meteorology, and gunpowder.
Ninjutsu is, in other words, a survival technique based on comprehensive knowledge.
Also, although few Japanese know it, there is a theory that “ninjas sold medicines”.
In the Middle Ages, medicine sellers in Japan were considered to have been a perfect profession for espionage, as they traveled around the region carrying medicines and entered their homes without being suspicious.
medicines can also be poisonous. In that sense as well, the theory that the medicine seller was a ninja is influential.