It was very long ago that i watched this anime.. its about a male teacher with a demonic right hand, that he hides by wearing a black glove. when his students get into trouble with bad spirits he'll chant something and 'release' his demonic hand, and rescues his students by killing the spirits,usually.

if i still remember correctly, its revealed later on that actually a very strong demon merged with that teacher, though i forgot how it happened.

in an episode its revealed that when he was a boy, his own teacher (female) was also one of the few with some powers, and she helped him keep the demon that merged with him in control. she died later in the story i think.

been trying to find out the anime/manga's name, but without success.. someone help please =)

jigoku sensei nube