Tetsuo Takahashi, an unassuming high school biology teacher, harbors a deep curiosity for Demis, or Ajin—hybrid beings coexisting with humans. In his quest for understanding, Takahashi engages with three Demi students at Shibasaki High School: the lively vampire Hikari, the soft-spoken dullahan Kyouko, and the timid snow woman Yuki. Amid his interactions, Takahashi crosses paths with the reserved succubus teacher, Sakie Satou, who shies away from men. Through casual interviews, Takahashi delves into the Demis' unique traits, emotions, and integration into society. As bonds form, Takahashi discovers that these extraordinary beings are more relatable than he ever imagined.