Genji choja (源氏長者)
"Genji choja" means the head of the Minamoto clan. In principle, a person who had the highest court rank among the persons of Minamoto clan became Genji choja. In the Minamoto clan, Genji choja had various authorities relating to religious service, summons, litigations and recommendation of promotion. It is generally believed that Genji choja concurrently assumed the position of the betto (superintendent) of both Shogakuin (a private school of the Ariwara Family) and Junnain (a family school named for the Summer Palace of Emperor Junna). However, Chikafusa KITABATAKE, who was Genji choja, explained in his book "Shokugensho" that being the Shogakuin betto satisfied the requirement to become Genji choja (in this case, the deputy becomes the Junnain betto).
Summary
Originally, Genji choja came from the Saga-Genji (Minamoto clan). The first Genji choja is believed to have been Sadaijin (minister of the left) MINAMOTO no Makoto (court noble). However, judging from the fact that the post of Junnain betto was created in 881 and Shogakuin itself was founded in the same year, it is presumed that either MINAMOTO no Toru, who was then the highest-ranking court noble among the people of Saga-Genji as well as the whole of Minamoto clan, or his son MINAMOTO no Noboru was the first person who concurrently assumed the betto of both schools and Genji choja. Provided, however, that as Shogakuin itself was the facility for all of kobetsu-shizoku (families branched out from the Imperial family), there is a possibility that its betto was not Genji choja but the choja of all such families including the Taira clan and the Ariwara clan. In other words, there is a possibility that Genji choja was not identical with the betto of both Shogakuin and Junnain.
(according to "Shigenki" (dated August 1, 1188), MINAMOTO no Michichika mentioned that there were cases where persons whose maternal grandfather belonged to the Minamoto clan were appointed to the betto (of both schools or of Shogakuin), and cited the name of FUJIWARA no Tasumoto and FUJIWARA no Yukinari as examples. They may have been Genji choja concurrently, but there is no firm evidence)
Further, Genji choja in early times were limited to being the court noble of Saga-Genji ("Saikyuki" volume 13), and the court nobles of Saga-Genji dominated this position up to the last court noble of Saga-Genji, MINAMOTO no Hitoshi (provided that FUJIWARA no Tasumoto once assumed this position concurrently with the In no betto (chief administrator of the Retired Emperor's Office). Later, Imperial prince Shigeaki and MINAMOTO no Takaaki (Daigo-Genji), whose maternal grandfather was a person of Saga-Genji, were appointed to Genji choja. Since then, persons of Daigo-Genji typified by MINAMOTO no Takaaki and those of Uda-Genji typified by MINAMOTO no Masanobu were appointed to this position alternately.
Thereafter, MINAMOTO no Morofusa (adopted son of kanpaku (chief adviser to the Emperor) FUJIWARA no Yorimichi) of Murakami-Genji was appointed as Genji choja, and since then, MINAMOTO no Masasada and his descendants, namely persons of the Koga family, the Horikawa family, the Tsuchimikado family and the Nakanoin family who were deemed as the direct descendants of Morofusa, inherited this position.
(except for the case where Michisuke KARAHASHI, a son of MINAMOTO no Michichika, and Masanori KARAHASHI, Michisuke's son, were appointed after the death of MINAMOTO no Michichika, the case where Michiteru KOGA's son Masatada NAKANOIN (a different family from the Nakanoin family) was appointed in the era of the Emperor Kameyama, the case where Chikafusa KITABATAKE of Kitabatake family, a branch family of Nakanoin family, was appointed in the era of the Emperor Godaigo due to the lack of appropriate person in the four families, and the case where Arimitsu ROKUJO of Rokujo family, a branch family of the Koga family, was appointed in the era of the Emperor Komyo)
In 1288, Michimoto KOGA was appointed to Genji choja for the first time. Thanks to the extinction of both families of Horikawa and Tsuchimikado, the decline of Nakanoin family and the political maneuver by Arimitsu ROKUJO, who had a sense of crisis for the appointment of Chikafusa KITABATAKE and Arimitsu ROKUJO, the monopolization of Genji Choja by the Koga family of Murakami-Genji became firm in the Muromachi period.
Yoshimitsu ASHIKAGA of Seiwa-Genji became Genji chaja for the first time as Buke-Genji (Minamoto clan as samurai families). The Ashikaga Shogunal family and the Tokugawa Shogunal family starting from Ieyasu TOKUGAWA became Genji choja while being samurai family (they insisted that they were the descendants of the Nitta family of Seiwa-Genji). After Yoshimitsu, however, only four of the Ashikaga shogun were appointed to Genji choja, namely Yoshimochi ASHIKAGA, Yoshinori ASHIKAGA, Yoshimasa ASHIKAGA and Yoshitane ASHIKAGA, and the total number was five persons inclusive of Yoshihisa ASHIKAGA, who was de facto choja (He served as the betto of both Junnain and Shogakuin. Some people asserts that he served as Genji-choja as well). Actually, Ashikaga family of Seiwa-Genji and Koga family of Murakami-Genji served as Genji choja alternately (the former's tenure was longer than that of the latter). In the Sengoku Period (Period of Warring States), persons from the Koga family of Murakami-Genji were appointed to Genji choja. The Tokugawa family monopolized the position of Genji choja beginning with Ieyasu TOKUGAWA. Provided that Tomohiko OKANO presumes that Tatemichi KOGA once became Genji choja at the time of disorder in the end of Edo period.
Genji choja was merely the highest title among Minamoto clans after the collapse of the Ritsuryo system. On the other hand, there is a theory, which is based on the theory of Yoshimitsu ASHIKAGA equals the King of Japan, that Ieyasu TOKUGAWA saw the advantage of its authority, and changed himself from Fujiwara cognomen to Minamoto cognomen, obtaining power equivalent to that of the King of Japan by becoming both seii taishogun (literally, great general who subdues the barbarians) and Genji choja and used such power for controlling both court nobles and samurai families (Tomohiko OKANO). However, the above theory is not accepted commonly.