Atsumi Kakunoshin, also known as Kaku-san, is a samurai retainer and bodyguard who travels across Japan in the service of Mito Mitsukuni. He maintains a studious demeanor, a notable contrast to the more fun-loving nature of his fellow retainer, Sasaki Sukesaburō. In the animated adaptation, his physical capabilities are a focal point; he is a strongman possessing the strength of a hundred men, a power he employs to defeat adversaries in combat. His primary role involves investigating local injustices and mysteries in the villages they visit. After demonstrating his combat prowess, he often participates in revealing Mitsukuni's identity by presenting an inrō, an act which leads to the judgment of wrongdoers. The character is occasionally accompanied by his wife, Miyuki, during some narrative arcs.