The novel opens with a scene in which 18 elite members of the Ohara family place their hands in front of themselves and chant the famed spell: "rin, pyo, to, sha, kai, jin, retsu, zai, zen." The incantation is illustrated as "a ritual performed by Koka ninja before battle to pray to the sun and the moon." In October 1487, Shogun Ashikaga Yoshihisa (1465-1489) of the Muromachi Shogunate mounted a campaign to subjugate Sasaki Rokkaku Takayori (1462-1520), the military governor of Omi province in what is now Shiga Prefecture. The Koka clan rallied to the Rokkaku side, staging a night attack on the shogunate's war headquarters and ultimately defeating the enemy. Of the 53 families fighting in the war, 21 related groups that distinguished themselves in battle received letters of appreciation from the Rokkaku clan. The novel states: "The Koka clan has since been called the Koka 53 families or Koka 21 families, with its reputation for outstanding battlefield performance spreading throughout the country." The Ohara family is believed to have had especially close relationships with Tokugawa Ieyasu (1543-1616). The book is filled with anecdotes in this regard. In the Honnoji Incident of June 1582, powerful warlord Oda Nobunaga (1534-1582) ended up committing seppuku ritual suicide following a rebellion by his vassal, Akechi Mitsuhide, who coincidentally died the same year. Upon learning of Nobunaga's demise during a visit to Sakai in today's Osaka Prefecture, Ieyasu rushed to his base, Okazaki Castle, in present-day Aichi Prefecture, through the mountains of the nearby Koka and Iga regions.