Nagasa District, Chiba Nagasa District was an administrative district of Japan located in southern Chiba Prefecture.HistoryNagasa District was one of the four districts created in former Awa Province on April 1, 1889. Much of the area of the district was part of the former Hanabusa Domain. At the time of its foundation, the district consisted of two towns and nine villages. On April 1, 1897, Nagasa District was merged into Awa District, Chiba.