Oniwabanshū

The Oniwabanshū (お庭番衆) was a group of onmitsu government-employed undercover agents established by the 8th Tokugawa shogun, Tokugawa Yoshimune (1684–1751). They are sometimes described as "ninja".

History
During the Edo period, onmitsu (the term meaning a spy or an undercover detective) acted as secret agents in security and espionage functions, mainly intelligence and information gathering, sometimes with aid of kobushikata, small groups of lower-class agents posing as mobile manual laborers and working under Iga ninja supervisors. The oniwaban followed a strict set of regulations, which, in some cases, forbade them from socializing with the general public.

Tokugawa Yoshimune established the Oniwabanshu as an elite cadre of originally about 20 handpicked onmitsu, providing him with information about daimyo feudal lords and shogunate officials, while also protecting high-ranking officials of the government and acting as security guards in the Edo Castle. They were possibly quartered in the garden of the castle, hence the name.

According to some sources, during the tumultuous time of the Bakumatsu revolution the oniwaban were even sent to the United States to spy not only on the shogun's opposition, but on the Americans as well.

In popular culture
The Oniwaban have been depicted as the main characters in the television series Ōedo Sōsamō (an undercover group of secret agents, including Isaka Jūzō, Jūmonji Koyata, Konami and others) and Shōgun no Onmitsu! Kage Jūhachi (the group of Kanō Ametarō: Miki, Otojirō and Inokichi, brought together by Tokugawa Munetada) and in the film Oniwaban (known in English as Demon Spies). They were also featured in the TV series Abarenbō Shōgun (being the spies and bodyguards for Yoshimune, including Akane, Ayame, Gorōta, Hayate, Osono, Jūmonji Hayato, Koyuki, Kaede, Nagisa, Ōtsuki Hanzō, Saizō, Satsuki and Sukehachi), as well as in the manga/anime series Ga-rei (Hattori Naizou, a member of the Judgement Day brigade, was an Oniwabanshu in life), Gin Tama (Ayame Sarutobi, Zenzo Hattori and Jiraia), Lone Wolf and Cub, Peace Maker (Shinsengumi member Yamazaki Ayumu), Samurai Champloo (Kariya Kagetoki), The Dagger of Kamui (the oniwaban monk Tenkai) and Yoshimune (the character Kunoichi, in love with the titular character). The first Shadow Warriors TV series has Oniwaban existing under Tokugawa Ietsuna, the fourth Tokugawa Shogun, but they are Kouga Ninja working against the Iga Ninja.

Some depictions feature the oniwaban in a time period following end of the shogunate, like the manga/anime series Rurouni Kenshin (featuring the now-unemployed Oniwabanshu group including Aoshi Shinomori, Beshimi, Han'nya, Hyottoko, Okina, Shikijō and Makimachi Misao ) and Yokujō Climax (Hayato); others take place in an altogether fictional alternative worlds, even in the futuristic science fiction setting, such as in the case of the anime Chou SD Sengokuden Bushin Kirahagane (Jyuuha Gundam), the video game Red Earth (Oniwabanshu leader Kenji) and the miniatures game Inifinity. In the anime series Sailor Moon the name of the villain of the week Oniwabandana (renamed Ninjana in the English version) is also an obvious pun on the oniwaban.