In this event, there is a crisis at the Scarlet Devil Mansion, and the only cure is ... maids! Apparently they need all the maids they can muster, so everyone is putting on maid outfits, even Patchy!

The event is still in progress, and the whole story hasn't been unlocked yet, so I don't know what Patchy is supposed to be knitting or how it relates to the plot. The name for her outfit, "High Dexterity Maid for a Week" is just hilarious.