This is why Ishido essentially does Lady Ochiba's bidding since he also acknowledges the Council of Regents' lack of legitimacy. Shogun is an FX original mini-series set in 17th Century Japan.
Lady Ochiba's tragic past is revealed to be linked ... Lord Yoshii Toranaga is based on the real-life shogun Tokugawa Ieyasu, who claimed to be a direct descendant of the esteemed Minamoto clan.