Hell Teacher: Jigoku Sensei Nube Season 1 Episode 13
The Human Faced Tumor
Nube is not showing up for school, and there are rumors about a mysterious person living in the old school building. Hiroshi and his friends sneak into the building to investigate, only to find Nube possessed by a demon and unable to use his Demon Hand. Now his students must muster all their courage to save their teacher.