Sensei, Kowai Hanashi Shimasenka?
what I think is- basically Hizuki and Magaki are the gods Akatsuki and the other one I can't remember the name of (lmao) but since Hizuki's powers are too much to handle for him he starts to see and attract ghost and other supernatural stuff, and all of that makes him feel overwhelmed and therefore, weak. However, since Magaki it's also one of the gods he can help him balance his power through sex, while taking some of it. And about Ajiro- I guess he was traumatized, because he was the one who found out the corpse of his dead sister in the pond while she was looking for the keychain, he thought someone killed her so he wanted revenge, but since there wasn't a clue about the so called "murderer" he couldn't do nothing but instead make a ritual, that's why he told the story about the baby and the thieves, he wanted to do the same and that's why he killed Sakuraba and that other woman found under the cherry tree, so he could take their body parts to make a doll where his sister's soul could enter and try to bring her to life by sacrificing Hizuki. The ghost in the school were Sakuraba and Asami all this time because they wanted to let Hizuki know who was the murderer. Also, in "Kaidan BL" there's a prequel of the story that tell us more about Hizuki, it seems that he's so powerful that makes humans he haves sex with to end up committing suicide since they can't handle those powers and drives them crazy.
Zantei Boyfriend