The Komugi family cake shop, Sugar & Spice, has fallen on hard times. What was once a sprawling business, built up by Nanoha's grandfather, fell apart as soon as her father succeeded the business.

Suddenly, aliens invade. Their scanner identifies a cake as a potent superweapon able to change the course of the Galactic War. So the private leading the invasion decides to investigate further by baking cake with Nanoha.