Nico Wakatsuki completes her witch training and moves in with her childhood friend Morihito Otogi, an ogre whose family has served as familiars to hers for generations. A prophecy gives Nico one year before a great calamity reaches her, and Morihito is charged with guarding her until it passes. He takes the job seriously; Nico's experimental spells, cast with more enthusiasm than precision, turn their daily life into a parade of magical mishaps that pulls classmates and supernatural neighbors into the household.