Naruto

In their history, ninja groups were small and structured around families and villages, later developing a more martial hierarchy that was able to mesh more closely with samurai and the daimyo.[citation needed] These certain ninjutsu trained groups were set in these villages for protection against raiders and robbers.[citation needed]

Ninja museums in Japan declare women to have been ninjas as well. A female ninja may be kunoichi (くノ一); the characters are derived from the strokes that make up the kanji for female (女). They were sometimes depicted as spies who learned the secrets of an enemy by seduction; though it's just as likely they were employed as household servants, putting them in a position to overhear potentially valuable information.[citation needed]

As a martial organization, it has been assumed that ninja would have had many rules, and keeping secret the ninja's clan and the daimyo who gave them their orders would have been one of the most important ones.[citation needed] For modern hierarchy in ninjutsu, see the article about ninjutsu.