Kitano mandokoro (北政所)
Originally, Mandokoro indicated a household-handling organization (an office handling private affairs concerning the family and residence) whose establishment was permitted only for imperial princes and kugyo (top court officials) who held the rank of Sanmi (the third rank) or higher.
In a Shinden style residence during the Heian period, a private living quarters called 'Kitanotai' was built north of and separated from 'Shinden,' which was the main hall and was used semi-publicly, and in that quarter, its master called 'Kitanokata' who was the legally wedded wife controlled all of the houshold affairs. The reason why the position of a legally wedded wife was so strong is that a nobleman married his bride to enter her family, and therefore, his residence was originaly owned by her family.
When the master of the residence advanced to a position of sanmi and opened Mandokoro, the 'Kitanokata' was called 'kitano Kandokoro.'
Examples in the Taira family
However, the legally wedded wives of Sessho or Kanpaku were called 'Kitano Mandokoro' for generations, and it also happened that a number of Kitano Mandokoro existed at the same time.
For example, in a portion of vol. 1 of "The Tale of the Heike", the daughters of TAIRA no Kiyomori were introduced as follows:
……One of his daughters became the Kitano Mandokoro of Sesshodono at Rokujo.……His other daughter became the Kitano Mandokoro of Fugenjidono. One more daughter of his became the Kitano-kata of Reizei Dainagon (chief councilor of state) Takafusa.
In this description, the 'Kitano Mandokoro of Sesshodono at Rokujo' indicates Mitsuko, who was his fourth daughter and she became the legally wedded wife of FUJIWARA no Motozane in the position of Kanpaku, and the 'Kitano Mandokoro of Fugenjidono' indicates Sadako, who was his sixth daughter and she became the legally wedded wife of Motomichi KONOE in the position of Kanpaku. The 'Kitano-kata of Reizei Dainagon Takafusa' indicates the legally wedded wife of FUJIWARA no Takafusa, a court officer loved by Emperor Goshirakawa, and she, though being a legally wedded wife, was called 'kitano-kata,' not 'kitano Mandokoro,' because Takafusa did not become Sesssho nor Kanpaku.
Ho-taiko and Kitano Mandokoro
Towards the end of the Sengoku period (period of warring states) that was long after the period described above, Hideyoshi TOYOTOMI became Kanpaku, then became Taiko after he handed over the Kanpaku postion to his nephew, and the term of Taiko, 'which had indicated ex-Kankaku who handed over the position to his son or brother,' came to indicate Hideyoshi alone. Similarly, 'Kitano Mandokoro' which was the generic term for 'the legally wedded wife of Sessho or Kanpaku' came to be used only for indicating Kodain, the legally wedded wife of Hideyoshi, after the title was given to her.
As the title of 'Kitano Mandokoro' was given to the legally wedded wife of Sesshu or Kanpaku, that of 'Okitanomandokoro' or 'Omandokoro' in short was given to the mother who gave birth to Sessho or Kanpaku. This term had been a generic one as well, but after the title was given to the mother (Naka) who gave birth to Hideyoshi, the term came to be used for indicating her alone.