First District (termed District One in the English) is an organisation in Mai-HiME. First District is responsible for the identification and gathering of HiMEs at the Fuuka Academy, in order for the HiME Carnival to take place.

First District is headed by three elderly figures and has many characters in the series on the payroll, including Mashiro Kazahana, Fumi Himeno and Nagi Homura. Two of the Academy's teaching staff, Kaiji Sakomizu and Wataru Ishigami, also work for the organisation. Saeko Kuga formerly worked for them, but was killed by them after she attempted to sell her daughter Natsuki, a HiME, to the rival Searrs Foundation. In light of this engineered death, Natsuki has dedicated her life to exposing and combatting the First District. Ultimately, First District answers to the Obsidian Lord.

Their modi operandi include attending all Orphan-related incidents, covering up HiME/Orphan activity through manipulation of media and altering the memories of witnesses to and people involved in such incidents.

Much of the First District, including the three leaders, was destroyed by Shizuru Fujino during her rampage, on behalf of Natsuki, the object of her ardour and Most Important Person.