In the mid-Tokugawa period, a conflict arose over the "Seiryū Himon," a secret document left by the former shogun Iesai, bequeathing the eighth shogunate to young Lord Manguro of Owari domain. This document became the center of a struggle between the current shogun, Yoshimune, and Manguro. Iida Daisuke, a member of the shogunate's secret intelligence group, the Kurokuwa Group, stole the document from Owari but was killed by Manguro's men. The document then fell into the hands of Yozakura Ogin, who had pledged her life to Daisuke.