Wikipedia posted:

One day in the near future, the Japanese Self-Defense Force decides to transfer the command (and financing) of their air force to private companies and investors. Most reject the idea as a joke, but some show business-oriented companies catch up on the idea, spawning the birth of a new type of idol: the so-called "Idol Pilots", celebrity combat pilots.

The five Toreishi sisters, Kanna, Yayoi, Satsuki, Uzuki and Mina, are teenage idol singers who are collectively known as The Hummingbirds. They are also one of the ace fighter pilot squadrons in the Japanese military. When they aren't saving the world from major overseas threats, they are on stage in frilly dresses, pursuing their idol career. This is the story of how they came to be Japan's most successful idol group and their first line of defense.