Upotte is a manga about girls that are guns. In essence, they are living guns. In their girl form, they have a special affinity for using the gun that they are the living representation of. More info and where to get scanlated versions via:
http://www.mangaupdates.com/series.html?id=45851 Picture is of "FNC" who is one of the female assault rifles attendind the local academy. Rifles with short or abbreviated assault stocks may manifest in things like T-back pantsu in their female form.
