Morihito Otogi, a high school student who carries the blood of an ogre, has his quiet life upended when his childhood friend Nico Wakatsuki returns home after completing her witch training. Nico, a clumsy but well-meaning witch-in-training, has a very specific goal in mind: to claim Morihito as her familiar, a role usually reserved for animals like cats or bats. Due to an old pact and a dire prophecy that foretells a calamity befalling Nico, Morihito reluctantly accepts this duty, which also involves them living together under one roof. While Nico is overjoyed to be reunited with her longtime crush, Morihito remains mostly oblivious to her feelings, focusing instead on protecting her from danger and the constant, unpredictable chaos caused by her magic.

The story is set in a contemporary Japanese town where magic and supernatural beings exist just beneath the surface of everyday life. Morihito and Nico attend Asunaro Private High School, where they try to keep Nico’s magical abilities a secret, though their efforts often fail spectacularly. Their household quickly becomes crowded with other supernatural protectors and friends. The first to arrive is Kanshi Kazamatsuri, a tengu who can control wind and acts as Nico’s crow familiar, bringing a sharp Kansai dialect and a competitive streak against Morihito. They are later joined by Keigo Magami, a werewolf who transforms into an arrogant and powerful alter-ego called Wolf whenever he sees a crescent shape, and Miharu Kiryu, a blunt and unfiltered young vampire who carries a parasol to block the sun. The group is frequently visited by Nemu Miyao, another witch who can transform into a black cat and repeatedly tries to recruit Morihito as her own familiar, only to be thwarted when he pets her into a deep sleep.

Notable narrative arcs in the series balance episodic supernatural hijinks with character-focused stories. Early episodes establish the core premise as Nico’s spells inevitably backfire, from accidentally shrinking the group to creating living paper animals. A significant recurring threat emerges from a mysterious stimulant called a drop that amplifies desires and strength, leading to the two-part Dogs and Raindrops arc where Keigo’s werewolf powers spiral out of control. The series also explores the broader magical world when Nico receives a prophecy from her mother, Ibuki, tasking the group with finding an ancient retainer to exorcise a summer demon. Interspersed with these action-oriented stories are comedic arcs that focus on the characters’ daily lives, such as Kanshi and Nico starting a disastrous online video channel, their teacher’s secret life as a manga otaku, and Morihito’s surprisingly intense passion for denim jeans.