Strike Witches (ストライクウィッチーズ, Sutoraiku Witchīzu?) is a light novel series originally created by Humikane Shimada (who also illustrated) with Projekt K, and written by Noboru Yamaguchi. It was later adapted into two manga series, as well as an anime OVA directed by Kunihisa Sugishima and produced by Gonzo. The story revolves around teenage girls who are essentially moe anthropomorphizations of military planes. The OVA preview episode was released on January 1, 2007. A televised anime series later premiered on July 3, 2008.

Source: Wikipedia