Window Star

Madoka Kei is a girl who transferred into Southern Cross Academy's highschool division, 1st year class 2, along with Kou Atari. She’s a member of the Glittering Crux, Window Star. At first glance, she seems like a quiet, refined young lady, but she’s actually got such an extreme personality that Kanako Watanabe even described her as “really dangerous.”

(Source: Star Driver Wikipedia)