Kishidan no Elf-san Datte Otome ga Shitai.

In a famed kingdom, women are not allowed to enter the knighthood! And yet, a female elf becomes the temporary captain of that very order of knights?! Enjoy the daily life of the elf captain, Gilga, who is cool and powerful on the outside, but maidenly and pure on the inside!!
(Source: Manga UP!)