Both involve teenage girls, with impressive fighting abilities with weapons against monsters that they refer to as their enemy, though they are more or less exactly like them. Also, in both of these anime, there is a hint of developing feelings between the heroine and a character. If you like anime with girls that don't mind getting bloody, have a mature and slightly cold personality, and have an alter ego (Blood C), then I highly recommend this anime.
You have an avatar!
Welcome to Anime Planet!