This Anime falls under the category 'Shoujo' but it's more of a shounen due to it's action and violence. The relationship between Shion and Nezumi may seem Shounen ai but it's more of a best friend relationship.
As a Girl, I fell in love with it's art and find the male protagonist attractive but I'm more interested in it's action. The plot is a little bit confusing and there's a time I almost wanted to stop watching this Anime because I find it cliche, but in the end I finished it because there's a scene that suits my taste.
Overall, this is an Amazing anime.
But you should read the manga for satisfaction.
