Yamine

Yamine the Dark Deity or Dark Eyes is the main antagonist of the episode 15 of the Gakkou No Kaidan.

History
Yamine is an evil demon who simply steals the souls of their victims and erases them from existence. Prior to the events of the series, Yamine had already had owned a student named Shinobu Matsuba, and that she was not her classmate of Satsuki mother in the past. Then she under her Shinobu avatar manages to convince the girls to perform a black magic ritual including Satsuki. However, all girls who perform the ritual cease to exist, and when Satsuki decides to do the ritual. Amanojaku saves her and warns that she has been deceived. With that Yamine appears and asks him why he helps humans, that Amanojaku in his answer says he hates humans, but also hates ghost like her, so the two begin a confrontation. After Dark Eyes manages to defeat Amanojaku, and she goes to Satsuki's direction, which she had read in the diary as defeating Dark Eyes, she then ties her in a mirror with string-like paint and then she uses a camera that she uses to defeat Dark Eyes, and the girls she had erased came back into existence.