Katsute Mahou Shoujo to Aku wa Tekitai shite Ita.

Katsute Mahou Shoujo to Aku wa Tekitai shite Ita. (かつて魔法少女と悪は敵対していた., lit. "This is the first, and probably final, loose hostile relation") is a manga series by Cocoa Fujiwara. It was serialized in Gangan Joker.

Plot
The manga centers on Mira, the clever brains behind an evil organization that invades and destroys everything in its path. One day, a magical girl named Byakuya Mimori decides to stand up to the organization, and Mira falls in love with her at first sight.