"Occult Academy" is set in 1999 at Waldstein Academy, a private school in Japan dedicated to the study of the occult. The story centers on Maya Kumashiro, the daughter of the academy's late principal, who harbors deep resentment toward her father for his obsession with the supernatural. After his death, Maya reluctantly becomes the acting principal of the academy, determined to dismantle its occult-focused curriculum. However, her plans are disrupted when a time traveler named Fumiaki Uchida arrives from the year 2012, claiming that the world will end unless they prevent a catastrophic event tied to the academy.

Fumiaki explains that a mysterious object called the "Nostradamus Key" is central to averting the apocalypse. The key is said to be hidden somewhere within the academy, and its discovery is crucial to stopping the impending doom. Despite her skepticism, Maya is drawn into the search, partnering with Fumiaki to investigate paranormal phenomena and uncover the key's location. Their journey involves encounters with various supernatural entities, including ghosts, demons, and otherworldly beings, each tied to the academy's dark history.

As the series progresses, Maya and Fumiaki uncover secrets about the academy's past, including its connection to a powerful occultist and the true nature of the Nostradamus Key. Maya's personal growth is a key element of the narrative, as she gradually reconciles with her father's legacy and her own feelings about the occult. Fumiaki, on the other hand, struggles with his mission and the moral implications of altering the timeline to save the future.

The series blends mystery, supernatural elements, and character-driven drama, with a focus on the evolving dynamic between Maya and Fumiaki. Their partnership evolves from mutual distrust to a shared determination to prevent the apocalypse, even as they face increasingly dangerous threats. The story culminates in a high-stakes confrontation that tests their resolve and forces them to confront the consequences of their actions. "Occult Academy" combines a tightly woven plot with a mix of suspense, humor, and emotional depth, making it a distinctive entry in the supernatural anime genre.