Soukou no Strain

Sara Werec comes from a respected military family and when her brother Ralph leaves for the frontlines of an interstellar war she makes a promise to follow in his footsteps and join him one day. However the next time she sees her brother he has become a traitor and is leading an enemy attack on her training base. Defeated and disgraced, Sara loses her status in an elite military unit and now must start over as a common pilot and work her way back up so she can once again confront her brother. (Source: ANN)