The kunoichi (くノ一) are female ninja or ninpo practitioners. They were used as assassins and spies.
The usual training of the kunoichi differed radically in the skill set of the ninja, although they maintained a common core: taijutsu, ninjutsu, etc. They were specifically instructed in a unique set of skills that only a woman could use.
This technical range made the kunoichi a versatile tool against men. She was usually unaware of having female partners, as the commander constantly kept her in the belief of being the sole ward, as this ensured her effectiveness and loyalty through emotional bonding.
The main Jonin ninja of female clans was Chiyome Mochizuki of the Koga ninja family, who trained orphaned and destitute girls by treating them as nuns and using their services as spies.
The Kunoichi, as already mentioned, served as spies, seducing feudal lords to kill them or obtain important information. It is said that the beauty of the Kunoichi was so great that no man could resist their deadly seduction.
The ninja were trained mainly for seduction and that is why their teaching also covered sexual relations, even going as far as marriage to fulfill the mission.
The term is believed to derive from the name of the characters that resemble the three strokes in the kanji letter for woman (女 onna); it is said in the order in which they are written: ku (く) - no (ノ) - ichi (一).
Principles of literary quotations include Enshū Senkuzuke Narabi Nihyaku In (遠舟千句附并百韵) (1680), as well as Maekuzukeshū (前句付集) (1716), which specifically associates the word with the kanji 女 supporting the etymology . The writing of "く ノ 一" requires the use of one character from each Japanese system of writing - first hiragana, then katakana, and finally kanji.
While hiragana and kanji can exist in the same word, katakana generally cannot appear in relation to each other. There are exceptions to this, for example, "ゴミ箱", "消しゴム".
A folk etymology that derives the term from 九 能 一 (能 "nō": talent) with Japanese numerals "ku" (九) for "nine", the particle "no" (の) for "and", and "ichi"(一) for "one", literally translated as "One of nine". The meaning of this name is derived from the number of orifices in a female body.
A man has eight, a woman has one more (the vaginal opening) and also possesses the abilities to make use of this orifice. Another theory states that the term is apocryphal and coined in the writings of novelist Futaro Yamada.
During the early years, female ninjutsu practitioners follow the same training as their male counterparts, practicing alongside them. Later, their training focuses more on disguises, poisons, and using their gender to an advantage.
They usually disguise themselves as geishas, prostitutes, entertainers, fortune tellers as well as maids, which would allow them many opportunities to gain information or get close to a victim.
Female garments offered the possibility of hiding weapons between the folds of clothing. They learned to use the Tessen or Japanese fan, as well as to use chopsticks to hold their hair in the form of Bo shuriken.