Vividred Operation: Rei Kuroki

An quiet but lonely girl who was working for herself but like animals and owns a parakeet named Piisuke. She comes from another world that was allegedly obliterated, along with her parents. She was approached by a mysterious black crow who promised her that she would be able to restore her world and relive her parents if she assist the alien monsters called the Alone by destroying the Manifestation Engine that was the reason of her world's destruction, she accepted the offer and possesses a black winged bow which she use to fire glowing arrows into the Alone, giving them more powerful forms but bears a mark of feathers on her neck, which indicates how many arrows she can fire, and she will die once she use up all of her arrows. She carries around a key that can open portals to different worlds and the scarf is what was left of her parents. These are from Episodes 5 and 6.

Episode 5

Episode 6

GIFs