 If you liked
C³
|
 ...then you might like
Black Bullet
|
Although the story is different, it features a main female character, who is cursed and have supernatural powers to fight off opponents or monsters. They are not seemingly hostile, instead they are friendly, having emotions, and having a cutesy appearance. They sometimes fight alongside with the boy, having some firepower or some backup to help defeat their target.
C3 is basically a school comedy, that fights other cursed people, while Black Bullet is a post-apocalyptic setting, fighting monsters.