This is not of much value, maybe, since I didn't read past chapter 4 or so.
Still, any story about a war that's set in the present has to take account of modern armaments. Things like nuclear bombs and 50-rounds per second Gatling guns can NOT be successfully fought by one human, no matter how augmented. To set the stage for all the wonderful feeling and philosophy and suchlike in this mange you have to give the girl amazingly massive powers that a reader can still swallow despite their excessiveness because they come from a familiar tradition, i.e., magic. Note how much time in Magister...Negima! the author spends in filling in lots of detail of how magic works so that when 10-year-old Negi fights the bad guys with giant magic effects it doesn't just seem ridiculous.
This is why I hate fantasy in most cases. It makes the writer or mangaka's scene-creating job a piece of cake. He can just massively rearrange how the physical world works, or even IGNORE same, until he gets the world the way he wants it, and since some people will swallow that, his story sells. It's too easy.
One anime that actually went to the trouble to create a plausable world for the fantastic battle story to take place in is "Simoun".
To sum up, let me quote lbloodll in his review: "In addition I felt that if the author wanted to tell a story about the depth of love, he could have used any other wartime scenario."
Yes he could, and if he had, the story would have probably have been more affecting, because I think that even the person most besotted with fantasy can more easily generate truly deep, painful feelings within a story set in something like the real world than in any other kind. After all, if it's happening in something like the real world that the reader lives in, then OMG all that painful stuff might actually happen to him!