A Death Row Convict Teaches at a School of Magic

As a human being, Kanaki Taiga was a broken man. Being a monster with rationality, he was finally apprehended one day and sentenced to death. From there, through twists and turns, he was now a teacher at a school of magic. After three years of teaching, his school life began to undergo a transition in the spring of his third year as a teacher when a prodigy princess enrolled at the school. This is an action horror story that outright rejects the conventional school teacher story. — Description from novelcodex.org