The young Okkotsu has problem. When he is upset or annoyed, an huge demon manifests itself to exact revenge on whatever is hacking him off. He thinks the best solution is just to live in solitude, but a teacher at the eponymous High School thinks training is the answer. Together with three other students, he gradually begins to understand his powers and to a certain extent, control them. Snag in all this is that a former student at the academy has a grudge, is bent on revenge and is prepared to unleash demons galore against the young quartet and their mentor to ensure the destruction of the…