noun
detective sergeant
A police rank in Japan, roughly equivalent to a detective sergeant. Used in police organizations.
彼は警視庁の部長刑事に昇進した。
He was promoted to detective sergeant in the Metropolitan Police Department.
刑事 is a general term for a police detective, while 部長刑事 specifically refers to the rank of detective sergeant.
Compound of 部長 (ぶちょう, 'department head') and 刑事 (けいじ, 'detective'), referring to a senior detective rank.