Saishu (Chief Priest) (祭主)
Saishu was a post within Shinto priesthood that was set up exclusively in the Ise-jingu Shrine.
Summary
In ancient times, the post was classified as a Ryoge no kan (a class outside of the Ritsuryo system [a system of centralized government based on the ritsuryo code]). The Nakatomi clan (the Onakatomi clan) had been appointed to the post for generations before modern times, and the Jingikan (Shinto commissioner) (set up in July of 1869 independently from Daijokan (Grand Council of State) with the amendments to the Constitution of 1868) held the post concurrently.
The role of the post was to visit shrines in Ise and recite prayers conveying the wishes of the emperor to the enshrined deity during the Kinensai (prayer service for a good crop), Tsukinami-sai Festival and Kannamesai Festival.
When the shrine was an organization of the state, the Saishu was in charge of general affairs and the transfer of a deity in the Ise Shrine during Jingu Shikinen Sengu.
Posts using the name of Saishu were established in shrines other than Ise-jingu Shrine, but these posts were clearly different.
Atsuko IKEDA, for example, now serves as a Saishu which is a post assumed by women born from the Imperial Family after the second world war. This post is sometimes confused with Saigu (an Imperial Princess appointed to serve the deities of the Ise-jingu Shrine), but Saigu were maiden imperial women who had served in shrines until the post was abolished in the period of the Northern and Southern Courts (Japan).
Modern times
In modern times, the inheritance of the post by the Fujinami family was abolished as the hereditary system of shake (a family of Shinto priests serving a shrine on a hereditary basis) was repealed and the peerage was appointed to Jingu Saishu.
Later on, Saishu became an official post appointed by the emperor to an Imperial Family member or duke and was legally established by imperial edict to regulate the Ise-jingu Shrine.
After the war, the Ise-jingu Shrine was no longer affiliated with the state and became a religious corporation under the Shinto Directive and the Constitution of Japan.
Currently the 'regulation' for the shrine as a religious corporation provides that 'Saishu are to be appointed in obedience to imperial order.'
A woman originally from the Imperial Family assumes the post.
Due to the fact that Imperial Princess Kuninomiya Asahiko was the first Saishu of Imperial blood, her descendants often assume the post. Although Atsuta-jingu Shrine had planned to set up a Saishu post, the plan was not implemented.