ソ・ラ・ノ・ヲ・ト
Sound of the Sky is an original military/slice of life drama-comedy. It was directed by Mamoru Kanbe, written by Hiroyuki Yoshino, scored by Michiru Ooshima, and animated by A-1 Pictures for the winter 2010 season. Private Kanata Sorami joins the military as a bugler and is stationed in the city of Seize with the 1121st Platoon.
Throughout the normal run of the anime there are exactly zero airplanes, or indeed flying machines of any kind. The world itself is post-apocalyptic where technology has regressed to roughly that of the 1930s or 40s. The heavy machinery of choice in this world are the tanks, which are quadrupedal and based off a highly-advanced pre-war design.
For its complete lack of airplanes, especially in a setting that seems so ripe for them, Sound of the Sky earns itself 0 out of 5 Airplanes.
But wait, I said “normal run.” That means there must be more to it. In addition to the twelve episode series there were two OVAs released, episodes 7.5 and 13. We can safely ignore 7.5 to focus entirely on 13.
Kanata realizes that she doesn’t know what her dream for the future is, and goes around asking the other cast members what their dreams are, for reference. The dream that we are interested in is that of Lieutenant Rio Kazumiya. Through her we learn that aviation is one of the lost technologies and, while she has built a hot air balloon that she lets Kanata ride in, her real dream is reinventing the airplane and using it to explore beyond the wastelands in search of a way to keep the world from ending.
In the end, the OVA gets a Participation Ribbon, and Lieutenant Kazumiya gets a Gold Star.