Jun-Sessho (associate regent) (准摂政)
Jun-Sessho refers to the permission given by the Emperor to a Kanpaku (Chief Advisor to the Emperor) or minister to govern affairs of state as a Sesshu (regent) under the Ritsuryo system, and it also refers to the person who received this permission.
Ryoge no kan (class outside of the Ritsuryo system)
There were 14 such examples between the middle of the Heian period and the end of the Edo period.
There were two ways that a Jun-Sessho could be appointed.
The first type was when an emperor who ascended the throne in his early years celebrated his coming of age. When an emperor was young, a Sessho was placed. However, when the emperor celebrated his coming of age, the Sessho submitted a letter for returning the right of handling political affairs to the emperor. Then the emperor dismissed the Sessho and appointed him to Kanpaku, and at the same time, proclaimed that he should become Jun-Sessho, giving him the same right as that of Sessho. In the latter half of the Heian period, when Emperor Goichijo celebrated his coming of age, FUJIWARA no Yorimichi was dismissed his Sessho post and was appointed to Kanpaku, and it was proclaimed that he should become Jun-Sessho. This was the first of such cases. Thereafter, when FUJIWARA no Morozane (in relation to Emperor Horikawa), FUJIWARA no Tadamichi (in relation to Emperor Sutoku and Emperor Konoe) and FUJIWARA no Motofusa (in relation to Emperor) were appointed to Kanpaku, they were also proclaimed Jun-Sessho (Tadamichi became Jun-Sessho twice). Though not clearly stipulated, in these cases the Jun-Sessho's term lasted until when the Emperor became around 15 years old.
The second type was when an emperor became ill. In these cases, the Kanpaku or the minister handled affairs of state like a Sessho while the emperor was ill. The first example of such a case was when Minister of the Left FUJIWARA no Saneyori became Jun-Sessho while Emperor Reizei was ill during the mid-Heian period. Then FUJIWARA no Michinaga, minister of the left, became Jun-Sessho while Emperor Sanjo suffered from an illness of the eyes. There was also a special examples, such as when during the Edo period Emperor Ninko died and the kanpaku Masamichi TAKATSUKASA became Jun-Sessho, following Michinaga's example. In these cases, the Jun-Sessho's term was not specifically stipulated, but came to end when the original reason for the appointment no longer applied.
When a Jun-Sessho was to be appointed, an imperial decree was prepared by both the Gekikata (officials from the Secretaries's Office) and the Daijokan (Grand Council of State).