As for episode 6 of Shogun, after episodes of gory violence...things quiet down a bit to focus on the women in the show. Usually I am not too keen on shows or episodes concentratring on women talk or "exploring women's inner lives etc", but in the Shogun context, I paid attention, because the story on Mariko and Lady Ochiba in this episode directly foreshadows major plot points in the story. What those plot developments are and what the fates of Mariko and Ochiba will be, I can't say of course (I don't want to spoil for those who haven't read the book), but I did notice they changed slightly the reason for Mariko marrying Buntaro, which the book gave a different reason.
I do like the fact Kiku was able in a way to become the "avatar" of Mariko, to express the feelings and connection between Blackthorne and Mariko when they cannot directly divluge their feelings to each other...yet. This episode explores why Ochiba became this villainous and manipulative Cersei Lannister-type character from Game of Thrones and especially how she seem to turn her initial powerlessness to later wanting "to spit at fate". George RR Martin is rumored to based Cersei on Ochiba, so you can think of Ochiba as a sort of "prototype" Cersei.