You are a civilian living in Mitakihara City. You've been attacked by a Witch after wandering into it's Labyrinth, and just as it was about to land the finishing blow on you, you get saved by something... A cat from the Cat Army, dressed up as a Magical Girl, wearing a wig, and holding a magical wand.

Magica Cat: Nyaa~ It was a close call, but I made it just in time! Or rather... Meow'd it just in time, heheh...