Benkan (Collective name of posts in Daijokan) (弁官)
Benkan collectively means the posts of Sadaiben, Udaiben, Sachuben, Uchuben, Sashoben, and Ushoben in Daijokan which is the highest organization of the Imperial Court. Its Chinese name in the Tang dynasty, i.e., Chinese style name, was Shosho.
It is commonly accepted that Benkan corresponds to Jo among the four official ranks, but there is another opinion that the bureau Benkankyoku including Benkan was established separately from Daijokan and Benkan was originally Honkan, which was not included in the system of four official ranks.
Daiben corresponded to Junior Fourth Rank, Upper Grade, and Chuben corresponded to Senior Fifth Rank, Lower Grade (Taihorei Kanirei.)
The prescribed number of Benkan was six as it was one for each of right (U) and left (Sa) Daiben, Chuben, and Shoben, respectively, but as provisional posts were permitted up to two for each of Chuben and Shoben, it was called 'Eight Ben.'
Later, as the prescribed number of the provisional posts established for Benkan was decided one, it was called 'Seven Ben.'
During the middle of the Heian period, Gon no Sachuben was established in many cases, but during the reign of the cloistered emperor, Gon no Uchuben was usually established.
The duties of Benkan was to direct and supervise the government offices; therefore, they were ranked higher than Shonagon later, and some officials concurrently held the posts of Sangi and Daiben. Some officials who concurrently held the posts of Kurodonoto and Daiben or Chuben were especially called Tonoben.
Sachuben was considered the first step on the ladder of the promotion to Third Rank or above, as the officials who served as Sachuben or above were qualified to be promoted to Sangi, but those who served as Uchuben and below were not qualified.
The duties of Benkan were mainly supervising the officials of the ministries and the organizations under the ministries, as well as administering the ruling of reception of general notification, examination and decision of the matters inside the government, signatures to drafts, judgment on delay or negligence in public services, night-watch duties of the government offices and morning ceremony Choshu of Kokushi (Taihorei Shokuinrei). Although it was prescribed that Sabenkankyoku was responsible for Nakatsukasasho, Shikibusho, Jibusho, and Minbusho, and Ubenkankyoku was responsible for Hyobusho, Gyobusho, Okurasho, and Kunaisho, it is considered that Benkankyoku was as a whole responsible for the eight ministries in fact.
Benkan had subordinates of Shi (ritsuryo system) (Sadaishi, Udaishi, Sashoshi, Ushoshi), Tsukaibe, Kajo, Shisho, Jikicho, and the like and formed left and right Benkankyoku with them. Benkankyoku was an important office that was in charge of practical business of Daijokan under the Giseikan (Daijin, Dainagon, Chunagon, Sangi), and was collectively called Daijokan Sankyoku together with Shonagon.
Daishi corresponded to Senior Sixth Rank and Shoshi corresponded to Senior Seventh Rank (Taihorei Kanirei), and until the Kamakura period, it became a practice that Sadaishijoshu was promoted to Fifth Rank and called Taifushi.
Daishi and Shoshi administered recording of received official documents, drawing up and signing of drafts, examining delay or negligence in public services, and reading up of official documents (Taihorei Shokuinrei.)
The others such as Shisho, Kajo, and Jikicho were Zoninkan without corresponding court ranks, and engaged in miscellaneous businesses including copying documents, announcing of an accuser, and the like. The prescribed numbers were two for each of left (Sa) and right (U) Daishi and Shoshi, ten for Shisho, and two for Kajo.
As Daishi and Shoshi, who were engaged in the practical business in Benkankyoku, were required to have a special skill of Sando and knowledge of practices in drawing up official documents, a sense of solidarity was formed among them; therefore, Sadaishijoshu which was the head of Daishi and Shoshi became a leader of Benkankyoku, presiding over Daishi and Shoshi.
After OTSUKI no Tomochika was appointed Sadaishi at the end of the 10th century, descendants of his stem family succeeded Sadaishi for generations. Around the 12th century, the Otsuki clan conventionally monopolized the post of Sadaishi. Sadaishi, which presided over Benmukyoku, was called Kanmu, and the Otsuki clan handing down the title of Kanmu for generations began to be called Kanmu family.