Influence of women on the imperial succession

[Prince of Camaria]

Being a new member, I do not know if this is the place to post this... there were "reigning" Empresses in the past in Japan, the more recent ones being MYOSHO (1629-1643) and GO-SAKURAMACHI (1762-1770). My real interest is in discussing the influence that women had on the succession through the years. Beginning with Fujiwara Fubito (Fuhito), who placed one daughter, Fujiwara Miyako-no-Iratsume, as a "consort" of Emperor MOMMU, ca. 697, and a second one, Fujiwara Asuka, as the Empress Consort of Emperor SHOMU, her nephew. The latter's son was Imperial Princess Takano, who ascended the throne as Empress KOKEN (749-758). Fujiwara Asuka was the fist non-imperial princess of the dynasty to be elevated to Empress Consort. These unions established the precedent for Fujiwara women becoming more "favorable" as candidates of potential mothers of future emperors than were daughters of emperors themselves!

Does anyone have suggestions as to English-text sources about the Imperial Family and their Fujiwara, Minamoto, and Taira (among others) wives and concubines?