Information Search
Ninja’s duties include ① information search in times of peace, ② soldiering to find out the enemy’s situation and terrain, ③ surprise attacks, and ④ guarding in times of peace (or war). First, let me explain about information search.
In the ninjutsu book “Shōninki,” it is written, ninja should search for information by disguising oneself as a trainee, merchant, or other person who travels around various countries. The historical record describes this as “七方出shichiho-de”. In fact, there is an example in the historical record of a “oniwaban” (a person who gathers information) who disguises himself as a merchant to search for information (Masaumi Fukai, “江戸城御庭番”), and the “Shōninki” is considered to be a realistic description of this.
Exploring the Enemy’s Situation and Terrain, and Making a Surprise Attack
When an army advances, it also has the role of checking to see if there are any ambush soldiers (soldiers in hiding). This is because ninja may take the enemy by surprise by becoming ambush soldiers (Masaru Hirayama, “戦国の忍び”). According to a historical document titled “Mikawa Monogatari”, the Imagawa family of Suruga Province made a surprise attack on Kariya Castle in Mikawa Province with fewer than 100 men and killed the lord of the castle. Because of the small number of men and the surprise attack, it is not possible to control the castle in a stable manner. To take control of the castle, you must wait for regular soldiers to come into the castle.
Guardians
During the Edo period, the main duty of the ninja was to guard castles and residences. A famous example of a guard is the Iga ninja of the Edo shogunate. They went to work in what is now called the office of Edo Castle in Haori Hakama ( a type of traditional Japanese clothing )(Yoshiki Takao, “忍者の末裔 江戸城に勤めた伊賀者たち”). The idea that “since they were good at surprise attacks, they could also be entrusted with guarding the castle,” as indicated in the historical document “Gunpōjiyōshū” led to the establishment of ninja who specialized in guarding the castle. The concept of the ninja’s duties basically remained, but changed with the times. (Yoshiki Takao)
