Satou-kun no Juunan Seikatsu

A 17-year-old boy named Satou, who is half demon and half human, attends a private high school in the demon world called Makkai as the only transfer student from the human realm. His face is permanently expressionless, which contributes to the unusual impression he makes on his classmates on the first day. He quickly annoys a prominent figure at the school, a reaper made of talking bones, who vows revenge for the slight. However, events involving Satou tend to unfold unpredictably.