Jundaijin (a government post) (准大臣)
Jundaijin was a government post in the ritsuryo system (a system of centralized government based on the ritsuryo code). This post was a Ryoge-no-kan position (an official position outside of the Ritsuryo system) that was positioned under the Nadaijin (Minister of the Interior) and above the Dainagon (Chief Councilor of State).
The person in this post was usually called Gido-sanshi (read the following). In the middle of the Heian period, FUJIWARA no Korechika was demoted to Dazai no sochi (Governor-General of the Dazai-fu offices) from Naidaijin, but was permitted to attend chogi (ceremony at Imperial Court) again. However, as there were no ministerial posts available at that time, his seat at the Imperial Court was located under the ministers but above the Dainagon, as ordained by an imperial order in 1005. In 1008, his post was made equivalent to the ministers and he was presented with 1,000 households (whose taxes served as his income). He then called himself Gido-sanshi. Later, use of this post as "Ryoge no kan" was established, and the Jundaijin post was introduced.
Gido-sanshi, which Korechika used to refer to himself, was used in the Sui and Tang dynasties in China as Kaifu Yitong Sansi (Supreme Minister), indicating a sankan, a position which was given, with no specific role provided, to civil officers at the rank of ju-ippin. In Japan, its original meaning of "the formal rank in rites is equal to that of the three ministers" was restored. This indicated that the post was equivalent to sanko (three high level bureaucrats), or Daijo-daijin (Grand minister of state), and Minister of the Left and Minister of the Right. Therefore, after Mototomo HORIKAWA (1232 - 1297) was appointed to the post in the Kamakura period, 'Gido-sanshi' was established as the Chinese version name of Jundaijin.
This was a government post given to the Tosho-ke (the hereditary lineage of Court nobles occupying relatively high ranks) whose uppermost rank available was determined to be Dainagon, such as the Urin family and some important noble families. In the Edo period, this post was coveted by Tosho-ke. The post was often given to a person loved by the Emperor or a maternal relative to the Emperor. It was customary that, when a person was to be appointed to the post, juichii (junior first rank) was given to the person prior to the actual proclamation of the appointment.