n the near future, Earth is at war with aliens called Worms. The war leaves the population of Earth decimated, with young men the main casualties. The Worms were beaten back but their re-emergence heralds the creation of a mecha unit called the Sonic Divers, piloted by 3 young girls to counter this threat.
The year is 1939 - it was then that the Neuroi appeared. Nobody knows where they came from or what their ultimate agenda is, but the fact remains that their attacks drove people out of their towns and cities. In order to take arms against them, humanity develops a new anti-Neuroi weapon called the "Strike Unit." Using the power of magic to fight against the monsters, this new devices enhances and amplifies the power of female magic-wielders. To use this devices, young witches from all over the world have been brought together to form an elite task force unit called the 501st Joint Fighter Wing, commonly known as the "Strike Witches."