Satsuki Kiryūin

Satsuki Kiryuin is the president of Honnoji Academy's Student Council and the first antagonist in the anime Kill La Kill, but later becoming a deuteragonist after her plans to overthrow her mother's Life Fiber fashion industry came to fruition.

She is later revealed to be the sister of Ryuko and the two join forces in order to defeat Ragyo in the climactic battle against the Life Fibers, who sought to enslave and destroy the human race.