Magical Girl with Demonic Time Magic

Setsuna Sh is a magical girl with temporal magic that allows her to go back to the past whenever she performs a certain action. She works as a magical girl, hunting monsters and helping people or at least, that's what she lets everyone believe. In truth, she made a contract with a demon so she could return to the past and rewrite the future.Her real reason for turning back time is to save her "sister." As a child, she had no parents, relatives, or friends. When she was finally adopted, her sister became her entire world and for her sake, Setsuna wouldn't hesitate to sacrifice the world itself. She gave up her original gender, her past "existence," and even parts of her freedom in a demonic contract, all for the sake of saving her sister and taking revenge on the monsters that hurt her.But is that really all there is to it? Or is Setsuna, in the end, partially responsible for everything that happened?