Somewhere between a fire-safety violation and a spiritual catastrophe, one hopelessly human teacher accidentally built a life among monsters — and now the monsters won't let him leave. Hyakki Academy runs on chaos, operates on youkai logic, and somehow, stubbornly, feels exactly like home.

Youkai Gakkou no Sensei Hajimemashita! is a comedy slice-of-life set inside Hyakki Academy, a middle school for supernatural beings hidden from the human world. The central joke is simple: one very human, very terrified rookie teacher accidentally took a job here and now can't leave — because, against all odds, it's become home.

The world sits in contemporary Japan but operates on youkai logic: school rules exist, but hallways rearrange themselves at night. There are parent-teacher conferences, but the parents are demons. The faculty lounge smells of incense and old fish, and nobody thinks that's worth mentioning.

The engine of the story is Abe Haruaki — a descendant of powerful exorcists who inherited the bloodline but none of the composure. His dormant spiritual power makes him genuinely dangerous to youkai, which means the school can't simply eat him and move on. His uniform fetish means the school won't stop tormenting him either. He screams constantly. He stays anyway.