noun
assistant inspector
A specific rank in the Japanese police force, below inspector (警部) and above sergeant (巡査部長).
彼は警部補に昇進した。
He was promoted to assistant inspector.
警部補は現場の指揮を執ることが多い。
Assistant inspectors often take command at the scene.
巡査部長 is the rank directly below 警部補, equivalent to sergeant.
Compound of 警部 (inspector) and 補 (assistant, supplementary). The term is a modern bureaucratic coinage for the police rank system.