Gretel is a member of the 666th TSF Squadron Schwarzesmarken, her call sign is Schwarzesmarken 04.

She is the political officer (commissar) attached to the 666th TSF Squadron to monitor morale and more importantly to ensure loyalty and that the squadron carries out its tasks in accordance to the will of the party and the people. As a political officer, she can supersede and countermand orders issued by the squadron CO. She also has the power to carry out summary executions on deserters and such.

(Source: Muv-Luv Wikia)