A life story of Atsuhime who was born in Kagoshima Prefecture, then called Satsuma, and became the wife of Tokugawa Iesada, the 13th shogun of the Tokugawa shogunate. She accedes to the highest rank in Ooku, the inner palace of the Edo castle where women related to the reigning shogun resided. Iesada dies soon after their marriage and Atsuhime assumes the name Tenshoin at the age of 23. She exerts herself for the Tokugawa clan and for the nation during the upheaval in the Meiji Restoration, headed by those from Satsuma. In 1835, Shimazu Tadatake, head of the Imaizumi-Shimazu family of Satsuma clan, and Oyuki are blessed with a long-awaited daughter, Okatsu, who later becomes Atsuhime. She grows up as a tomboy, full of wonders, yet warm-hearted. Meanwhile, as Satsuma clan is under going financial reform, headed by chief retainer Zusho, Tadatake is punished for being lenient with farmers. Okatsu, unable to absorb why her father is punished, charges over to Zusho.