The third Ooku series takes place during the 5th Shogun Tsunayoshi's (Shosuke TANIHARA) era. Ooku is completely controlled by the Shogun's mother, Keishoin (Kyoko ENAMI). Giving birth to the Shogun's two children, Tokumatsu and Tsuruhime, Oden-no-kata (Eiko KOIKE) is Keishoin's favorite concubine. Tsunayoshi's official wife, Nobuko (Norika FUJIWARA) - who came from the famous Takatsukasa Family in Kyoto - has no children yet. Coming from a very noble family, Nobuko always stands against Keishoin and Oden-no-kata, both who come from average households.
More than anything, Shogun Tsunayoshi loves to study. Since a very early age, Keishoin valued studies rather than martial arts and provided her son with plenty of education. Especially passionate about Confucianism, Tsunayoshi was eager to follow the "filial duties" (duties of a child to his parent) written in "The Analects of Confucius". That is why he devoted himself to his mother, and is at her beck and call.
Tsunayoshi has two close advisors that he trusts very much: Narisada Makino (Sei HIRAIZUMI) and Yoshiyasu Yanagisawa (Kazuki KITAMURA). The story begins when Tsunayoshi one day visits Narisada's residence.