Kunoichi indicates female ninja in the jargon of ninja (professional spies in Japan, highly trained in stealth and secrecy), and the use of females as a trick was called kunoichi no jutsu (art of kunoichi). However, in the world of novels and comics, the word kunoichi is often used to mean nyonin, or female ninja, and this meaning is prevalent. On the contrary, the use of male ninja was called the art of tajikara (probably because the Chinese character '男' is broken into '田' (ta, or rice field) and '力' (chikara, or force)).
Nyonin were sent to the enemy that they could not beat through physical strength alone, and were disguised as maid servants, whereupon they gathered classified information and committed assassinations. Therefore, the chances of nyonin doing the same job as the male ninja (who were dressed all in black) seemed rare.
However, there were risks that a nyonin would fall seriously in love with the enemy she was supposed to lure and thus betray her friends. In order to avoid this, it is said that a ninja who acted as a liaison and watchdog would constantly observe the kunoichi, and if she showed even a slight sign of betrayal the ninja would kill her mercilessly.
The origin of the word
Nowadays, the kunoichi is generally described as 'くノ一' (kunoichi), and the fact that the Chinese character '女' (female) can be broken into 'く' (ku), 'ノ' (no) and '一' (ichi) is supposed to be the origin of the term.
Hearsay regarding the term
The word 'kunoichi' means females and should be described as '九ノ一' (kunoichi, which means nine plus one). A human body has nine holes, including those of the eyes, nose, mouth, ears, navel and anus. It is also said that besides those holes a female has the vagina as an extra hole, which is why it is called kunoichi. The former theory that the character '女' can be broken into 'くノ一' came to be used as a familiar term for female ninja. However, the latter theory lacks clear credibility because, depending the material, the way of counting the number of human holes is different, including the theory that it includes the urinary hole, saving the navel.
Also, there is another theory that the word 'kunoichi' itself was coined by Futaro Yamada, the authority on ninja novels.
The novelist Shinjuro TOBE said in his book, 'Ninja To Ninjutsu' (Ninja and the Art of Ninja), that kunoichi originally came from 'kuichi no michi,' which indicates the art of the chamber bed in Onmyodo (way of Yin and Yang, an occult deviation system based on the Taoist theory of the five elements), and the Chinese character '九' and hiragana, whereby 'く' happen to have the same pronunciation and with the combination of '一' it becomes '女.'
History of kunoichi
The famous kunoichi group was Arukimiko (traveling shrine maidens), which served Shingen TAKEDA. Arukimiko toured many places in Japan and performed tricks and traditional Japanese dances, and occasionally provided sex for money. They were, so to speak, traveling yujo (prostitutes). In the Sengoku (Warring States) period, large numbers of children were orphaned, abandoned and deserted. Among such children, only those who were sound in mind and body were selected, and they were made into arukimiko and sent to various places as onmitsu (spies). Shingen ordered Chiyojo MOCHIZUKI, who was the young widow of Moritoki MOCHIZUKI, the head of the Mochizuki clan--the local ruling family in Kitasaku County, Shinshu Province--to make the girls into kunoichi. Actually, Chiyojo was a blood relative of the important family Mochizuki, and Moritoki MOCHIZUKI, who was a nephew of Shingen, became irimuko (a man who takes his wife's name) of the Mochizuki family. Shingen appointed Chiyojo as 'the chieftain of Miko both in the Kai and Shinano provinces' and opened the training hall called 'Kai and Shinano Miko do' in Netsu Village, Chiisagata County, Shinshu (the present-day Netsu, Tomi City, Nagano Prefecture) in which she taught 200 to 300 girls from jujutsu (an occult art), saying prayers to ninjutsu, art of self-defense and even an art of sex in case the enemy was a male. Arukimiko were called 'Nono,' and in Netsu Village, Nonokoji Street on which the miko's houses used to stand, and their graves still exist.
Because the arukimiko were allowed to freely cross the border and go everywhere, they gathered information, acted as liaisons with and reported everything to Shingen, performed kuchiyose (spiritualism) and dances, and sometimes prostituted themselves in the Kanto and Kinai regions (provinces surrounding the ancient capitals of Nara and Kyoto). However, Shingen, who was afraid of his vassals' rebellion, didn't allow them to give overnight lodging to Buddhist priests and arukimiko.