Both the manga and the anime feature a hotly contested war. Battles are shown through the lives of people on the front, but the diplomatic particulars of the war are not revealed to the audience. A reason is never given as to why the war broke out in the first place.

Although who the Japanese are fighting is never explicitly explained, in one episode an enemy plane is shot down near the city and the pilot's one or two lines are in near perfect American English. In the manga and OVA, Chise speaks to some English speaking enemy soldiers (with various accents), saying that she does not know much English, and later in the series there are some enemy soldiers that speak French. The OVAs also portray some of the soldiers speaking French. At the beginning of the OVA, Japan is attacked by Tornado jets, as used by European Air forces, and the attacking army is described as 'The Combined Forces'.

The only weapon of mass destruction observed in both the anime and manga was Chise herself, who by the middle of the story had the power to destroy entire cities and did so on a fairly regular basis. In more than one battle over a Japanese city, Chise simply vaporized the city and most of the people in it. In the OVA, one English speaking soldier from 'The Combined Forces' claims that Chise destroyed his home town.