It was Meiji 37 or year 1904 (somewhere in the timeline of Sakura Taisen). The Russo-Japanese war just started.

The story of this anime (based on a h-game by Elf) starts from when the Japanese army is getting readied to attack Port Arthur by establishing a training camp for female pilots in Hokkaido. Umakai Shintaro, a former diplomat who was residing in Russia once, is chosen to supervise the training.

Although five girls (Sanada Momen, Honda Sarasa, Katou Asa, Fukushima Kinu, Kuroda Rinzu and Ichijouji Sumi) who are assigned to him overwhelm him, his sense as a teacher brings him to guide these girls to complete their secret mission, although he does not even know what the secret mission is.