南西方面艦隊
In early 1942, "Nagatsuki" was assigned to escorting troop convoys from French Indochina for Operation J (the invasion of Java, Netherlands East Indies), From 10 March 1942 "Nagatsuki" and Destroyer Division 5 were reassigned to the Southwest Area Fleet and escorted troop convoy from Singapore to Penang, and Rangoon. The destroyer returned to Sasebo Naval Arsenal for repairs on 19 September, and rejoined the fleet on 9 November, continuing escort patrol duties.