Ruka Shihoudou

She is the high school's student council vice president who seemly has a disdain for all males except for Romio who is her "Instead," though she is the author it was her "Instead" who welds her killing tool called "The Pet Whip of Submissive Butchery" that turns people into submissive zombies upon being hit.

(Source: Otaku-streamers forum)