This anime series is set in 1920s New York where Sister Rosette of the Magdalene Order battles demons alongside her partner Chrono. He is an unlikely partner in the battle against evil as he is a demon himself; he has formed a contract with Rosette that controls his powers... at the cost of time off her life. Early on they fight demons-of-the-week but later their ongoing battle is with Aion. Aion is a powerful demon who is collecting individuals known as apostles for reasons that aren't immediately clear. One such person is Rosette's brother Joshua; another is Azmaria, a young girl who is rescued by Rosette and Chrono. As the series progresses they get closer to Aion but the danger to them and the world increases.

I rather enjoyed this series; it opens well with a deal of humour as it introduces us to the main characters and their world. This might lull one into thinking it will be light-hearted throughout but it does get darker in tone later on. The characters are solid; Rosette and Chrono are good protagonists; solid support is given by Azmaria and members of the Magdalene Order and Aion is a suitably menacing antagonist. The story is told in a way that gives the characters solid motives which we learn about as the series progresses. The character designs are good and the animation is of a high standard. Overall I'd say this is a series that is well worth watching.

These comments are based on watching the series in Japanese with English subtitles.