Strike Witches: Ribbons of the Sky

After the success of Operation Katina, Mobius 1, former Belkan ace Erica Klinsmann, and Narumi Miyamoto mysteriously disappear after being sent to investigate an unknown signal. Over the skies of Romagna, three mysterious Witches make a sudden appearance. How will these three veterans deal with a world that is at war with a belligerent alien race? Rated M for safety.