Cybersix (1999)

In the dark megalopolis of Méridiana, the silhouette of a mysterious character named Cybersix emerges, having escaped her creator, Doctor Von Reichter. By day, Cybersix, who adopted the male identity of Adrian Seidelman, is a literature teacher in a local high school and, by night, she 'transforms' back into Cybersix to fight Von Reichter's abominable creations and foil his plans. Soon, she's aided by her surviving brother, now named Data 7, a black bioroid panther.