Chrono Crusade (2003)

The Roaring 20's a time of prosperity. Jazz is king, the Mob rules the streets, and Demons are running a mock. Enter Sister Rosette Christopher, of the Order of Magdaline, an elite group out to destroy the evil. Along with her faithful companion and contractor Chrono, a devil, they go on wild gun slinging adventures. But Rosette's ultimate quest is to find her little brother Joshua, who was kidnapped by Lord Aion. Can Rosette save her brother?