柊 シノア

Shinoa is the main female protagonist and is the younger sister of Hiiragi Mahiru. She was appointed as Yuuichirou's supervisor during his suspension. She is a sergeant of the Japanese Imperial Demon Army and the leader of her squad in the Moon Demon Company. 

She has a sarcastic attitude and doesn't put much emotion into her words. Shinoa is somewhat perverted and enjoys teasing others at any opportunity. She generally tends to smirk before teasing or performing her antics at others, putting them in uncomfortable situations. She keeps many secrets. Although Shinoa is inexperienced, she leads her squad well and remains levelheaded in battle.

Because of her circumstances with the Hiiragi family, Shinoa grew up without knowing what a sibling even is and never truly cared about anyone until her current squad was formed. She greatly respects Yuuichirou's resolve and feelings toward his family and wants to help him.   

From url=http://owarinoseraph.wikia.com/wiki/Shinoa_H%C4%ABragiOwari no Seraph Wiki