Kokichi's biological father, who works as a minor official for the Tokugawa shogunate and takes a lenient approach toward Kokichi's behavior despite numerous misdeeds.

Kokichi's older half-brother, a respected Confucian scholar and district administrator who acts as a stabilizing force in Kokichi's life, trying to guide him and manage his troublesome actions.

Another half-brother to Kokichi, who is also adopted into another family and serves as a district administrator, maintaining a difficult relationship with Kokichi.

Kokichi's wife, described as a devoted and loyal partner, who faces numerous hardships due to Kokichi's behavior after their arranged marriage.

Nobuko's grandmother and Kokichi's adoptive grandmother, who has a poor relationship with Kokichi and is portrayed as treating him unfavorably.

Kokichi's only son, who becomes an accomplished naval engineer and official, rising to prominence during the Meiji Restoration and contributing significantly to Japan's naval development.