Akizuki Rokurōta was born as a child of Tokugawa Ieyasu, but since he is a twin with Tokugawa Iemitsu he is not allowed an official place within the Tokugawa family. Sent away as an adopted son, he continues his wandering journey. One day, he accidentally encounters Toyotomi Hideyori's son Toyotomi Hideya, his mother Katsura-no-miya Renko and their maidservant Sasaka, survivors of the Shogunate attack on Osaka Castle years before who are now fleeing from their refuge in Kyoto. The Tokugawa Shogunate and Yagyū clan are trying to capture or kill them, while on the other hand villains want to use them. Akizuki Rokurōta decides to protect them from both sides.

徳川家康の死後、その遺志を受け継いで柳生但馬守は朝比奈源右衛門に、豊臣秀頼の遺児・秀也とその母・桂宮蓮子の捜索を命じた。徳川の家に生まれながら、3代将軍・家光と双生児であったため、秋月六郎太は一人さすらいの旅を続けているが、ある日偶然秀也と蓮子を助け、彼らと行動を共にする