At first, one person was assigned to each of the Left and the Right Divisions, but two persons were assigned to Junior Lieutenant of the Left and the Right Divisions on June 9, 799, and then in 1148, the number of Senior and Junior Lieutenants dramatically increased to twenty in each Division.
当初はともに左右各1名であったが延暦18年4月27日に少尉が左右各2名制となり、久安4年（1148年）には大尉・少尉ともに一気に左右各20名に増加された。