Luminous Witches is an anime spinoff of Strike Witches (which I haven't seen). This is an alt-history WWII where aliens invade Europe (i.e. replace Nazis with mysterious aliens) and witches are young girls with magic abilities (which they lose in their early 20's I guess hence why they're all teenagers) that allow them to fly around and take the role of very maneuverable fighter planes.

In that world there are witches who don't fit well in the military. Former witch Grace Maitland Steward (Mikako Komatsu) decides to form a singing troupe of witches to go around raising morale like a USO troupe. She gathers representatives from the various armed forces, witches with erratic powers or who don't have the temperament for army life. The twelve-episode series is about forming the troupe, training them, then going on tour with various episodes highlighting a member or two and their back stories.

It's a pleasant story with interesting characters though I'd probably like a more action-oriented series like Strike Witches.