I watched the series once on the reccomendation of a collegue and did not like it much, it starts well but then they kill off the most interesting female, with no real warning and leave a huge hole in the potential plot, tho she does reappear at the very end of the series again..so they may have hoped to do a sequel. For many reasons it was not worth that and most fans were disapointed for it had a lot of potential, but falls flat over and over.
There is no real reason for the animosity of the main plot element..ie the battle between the main good guy and chief villan and it gets boring by the end sadly when it might have been ok if it were not the ONLY thing that the series ended up being about.
they tossed in their own verision of a "magical Girl" ie a female with super powers and dusted off a bunch of other borrowed elements and tried to give it a hyped up look and feel. Too bad for it might have been fun.