Daijirō Ōhara holds the position of Chief Patrol Officer at the police box stationed before Kameari Park in Katsushika Ward. As a Division Head, he is addressed as "Buchō" by subordinates. He supervises Kankichi Ryotsu, frequently reprimanding him for laziness and neglect of duty while imposing punishments for misconduct. Despite this disciplinary stance, Ōhara exhibits paternal concern toward Ryotsu, occasionally treating him "like the son he never had" and extending similar fatherly regard to junior officers like Keiichi Nakagawa and Reiko Akimoto. This multifaceted relationship includes camaraderie, such as inviting Ryotsu for post-work drinks. Ōhara sports a small, trimmed mustache and carries a stern demeanor befitting his senior rank. He commutes via public transportation, using buses and trains. Personally, he is married with one daughter, Hiromi, and later becomes a grandfather to her two children. His hobbies center on traditional Japanese arts: judo, kendo, tea ceremony (sado), bonsai cultivation, and calligraphy. Though often exasperated by Ryotsu's antics, Ōhara recognizes his street-smart ingenuity in business affairs, sometimes consulting him on commercial negotiations or purchases. During extreme situations triggered by Ryotsu's disruptions, Ōhara has pursued him in military-style vehicles like tanks while donning army costumes—exaggerated comedic escalations beyond standard protocol. Ōhara's established role remains consistent across spin-offs, films, and extended media without significant evolution or expanded backstory.