Gekijouban Anime: Bokura no 7-nichikan Sensou
劇場版アニメ ぼくらの7日間戦争
-Description
On the day before summer vacation, every boy in a first-year class of a downtown Tokyo middle school disappears. Was it some accident? A mass kidnapping? Actually, the boys holed themselves up in an abandoned factory on the riverbed. With support from the schoolgirls, the boys start a revolution against the adults from this "liberation zone." Source: ANN