Morihito Otogi, a high school student who comes from a lineage of ogres, enjoys a peaceful, ordinary life until his childhood friend, Nico, moves in with him. Nico is a witch-in-training, and chooses Morihito to be her familiar. While Nico is thrilled to reunite with her old friend and crush, Morihito is tasked with the perilous duty to protect her from a foretold calamity. Between the unpredictable chaos caused by Nico's magic, and the awkwardness of sharing a home, their lives become a whirlwind of supernatural hijinks and threats.