It tells us an adult court police story located in the Edo period.

(from ebookjapan):

Tenichibo, claiming to be the Shogun's son, rides into Edo with a piece of evidence. However, it would be a big problem if an impostor was allowed to meet the Shogun. Ooka Echizen therefore selects Hango, who is rumored to have "wolf's testicles" because of his temper, to determine whether Tenichibo is the real Shogun or an imposter.

Iigo Fujikake, his lieutenant Yuzo, and Tsurujiro run amok in the Minamimachi Magistrate's Office in this humanistic detective story.

A masterful work by the famous duo!