Hikojū is a member of the special police force led by Hasegawa Heizō, serving as one of the key operatives in the unit that controls arson and robberies in Edo. He is an old man of notably small stature, a physical trait that makes him exceptionally suited for his primary function as a spy and reconnaissance agent. Because of his diminutive size and ability to move unnoticed, Hikojū is frequently assigned to gather intelligence, often operating behind the scenes to obtain crucial information that determines the success of a mission. He stands out among the often grim and hardened members of the force due to his character, as he is portrayed as one of the most comical figures in the narrative, providing a lighter presence amidst the serious affairs of law enforcement. His role in the story is largely functional, focusing on infiltration and the quiet observation of suspects and criminal elements, using his unassuming appearance to his advantage.