The Oniwaban was a position in the Edo bakufu (the Japanese feudal government headed by a shogun) created by Yoshimume TOKUGAWA, the eighth Seiitaishogun (the Shogun in charge of conquering barbarian territories) in the Edo period. The oniwaban were the secret agents under the direct command of the shogun and accomplished the missions including intelligence collection.
Even though they were secret agents, their actual jobs were not so serious, for example, informing the shogun of the news in Edo city and visiting rural areas for inspection with their identity concealed. Their position was actually equivalent to the assistant of Oometsuke (senior inspector) and Ometuke (general inspector) under the direct command of the shogun. However, the image of oniwaban is generally a spy or ninja today and the oniwaban is frequently characterized according to such image in period dramas and novels.
According to the job class system of the Edo bakufu, the oniwaban was one of the Hiroshiki officials (inner apartment supply officers for Edo-jo Castle) which were organized with only men and belonged to Ooku, the harem of shogun. They were normally in the oniwaban guard station in the garden surrounding Honmaru (the main building where the shogun lived) in the property of Edo castle.
Their official duty was security but they sometimes conducted intelligence-gathering activities under the command of the aides of the shogun, Sobagoyotoritsuki (an attendant of the shogun who conveyed the shogun's messages and commands.)
They were also required to report any suspicious activities by regularly inspecting the feudal lords and vassals of the shogun as well as Edo city.
The oniwaban could get close to the shogun's palace due to their duty as the garden security guard and sometimes met the shogun in person to report the intelligence they collected even though they were just a Gokenin (retainers) which was the lower position than Omemie (the vassals with the privilege to have an audience with the shogun.)
They were in a unique situation in which they worked under the direct command of the shogun despite of their low position.
Thanks to their unique duties, they had a chance to make a great achievement and to get promoted. One of the oniwaban, Nagataka KAWAMURA was promoted to the high position with the property of 1000 crop yields according to Ashidaka system (the system to give low-class people extra property as wage when they got a higher position than their family class) for having worked as an Ongokubugyo (a magistrate placed at an important area directly controlled by the bakufu) at the end of the Edo period.
The predecessors of oniwaban were officials called kusurigomeyaku (gunpowder charger) in Kishu domain where Yoshimune was the lord before becoming shogun. In the Kishu domain, the kusurigomeyaku officially worked as security guard of the O-oku (the inner halls of Edo Castle where the wife of the Shogun and her servants reside,) but also conducted intelligence-gathering activities under the direct command of the lord like the oniwaban. When Yoshimune became shogun, more than a dozen of the kusurigomeyaku came to Edo with Yoshimune and were incorporated as Shogun's retainer to become his oniwaban. Although there were dozens of kusurigomeyaku in the Kishu domain, only a little more than a dozen of them were transferred to the bakufu. However, they were appointed just because they accompanied Yoshimune to Edo on their turn of duty but not because they were specially selected.
Yoshimune created the position of oniwaban because people from Iga and Koga who had worked for the bakufu since Ieyasu era, no longer functioned as ninja and secret agents. He also wanted his reliable retainers as his secret agents, who had worked for his family for generations, because he was a shogun from the Kishu family, a branch family of the shogun family. He also wanted to make the shogun power stronger by compensating the lack of inspection ability under the direct control of shogun because Ometsuke, the official senior inspector of the bakufu, actually acted as the ceremony officer whose main duty was conveying commands.
Social status and family lineage
The oniwaban was inherited by about a dozen descendent families of the kusurigomeyaku who were nominated as the first oniwanan by Yoshimune when they were transferred from the Kishu domain to the bakufu. The recruitment of oniwaban was rarely conducted. They kept the unity as the oniwaban family for generations and fulfilled their duties cooperatively.
The oniwaban families were originally lower-ranking vassals but most of them were promoted to the direct retainer of the shogun by the end of Edo period. When an oniwaban got a promotion, he naturally resigned the position of oniwaban which was for the lower-class retainers, however when his child stared working for the bakufu, the first position of this child had to be the oniwaban. The child of oniwaban who was promoted to a direct retainer of the shogun, became the oniwaban with the same ranking as the direct retainer.
They were also listed in the directory of Edo officials and their information was released including their name, address, income and resume even though they were secret agents.
Onkokugoyo (inspection trip to rural areas)
Onkokugoyo is the inspection trip to rural areas that the oniwaban made with their identity concealed. As previously mentioned, their performance as secret agents was not dramatic like the ninja as people generally imagine today, however the frequent onkokugoyo was one of their important duties.
The statements about oniwaban often say, 'As soon as the oniwaban received a mission, they went to a clothes shop owned by the bakufu, masqueraded as someone else in a secret room of the shop, and left Edo immediately with no notice to their family,' however, the oniwaban's writings and the bakufu's official records show that it was just a story.
In reality, they went back home once and prepared well for the trip prior to their departure when they received a mission of intelligence collection. They maintained close contact with the oniwaban families including the patriarch who had already retired from the oniwban after his promotion to the shogun's retainer. The oniwaban who had received a mission from the bakufu, discussed the investigation content with the patriarch of their family and the senior oniwaban. (However, they submitted an oath stated 'I hereby agree not to leak any confidential information during my duties to any third parties including my family' when they became the oniwaban. They also conducted a prior investigation in Edo to go on a trip with advance knowledge.
The investigation reports were made in writing and were reviewed by senior oniwaban before submission.
During the onkokugoyo, their absence as the garden security guard was officially treated as sick absence. The trip schedule recorded on their reports said that they had left Edo immediately after receiving a mission and reported their investigations as soon as they came back from the ongokugoyo, however they actually stayed at their house for few days before and after their trip to prepare for the trip and write investigation reports. They reported the untrue trip schedule because they needed to pretend as if they worked single-mindedly on their mission and also because the trip allowance was paid by the day.
In Kyoto and Osaka where the oniwaban often visited on the ongokugoyo trip, the purveyors were stationed as the local staff to support the secretive investigation by the oniwaban. The oniwan could accomplish their duties on their first onkokugoyo trip thanks to the purveyors' support.