I'm not highly skilled english user so you've gotta use your brain to the max level to understand my english.
While they were talking, the boy asked her why she's wearing glasses and that's because of a 'spiritual substance(?)' stuck through her eye. She said she had failed persuade her grandfather and made him angry. After that, she took something on his head away so that he felt fresh. I think this made a significant change. All of sudden, his older sister came into his room with fever. While he was at school, i saw many monsters, or ghosts, who were hanging on people who had injuries. Also one was on his left leg. He somehow was able to see them while normal people can't. Back home, he took care of his sister. And he noticed something. He had been feeling ill at ease with his sister before. But he acted normally taking care of her fever. He thought it was thanks to what the girl from first scene had done to him. Maybe a ghost had been making him awkward with his sister. But he thought there was something else started this awkward feeling. Reading the context in which he got horny with his sister, I think something had happened related to sex, maybe. At school, the girl satisfied his sexual desire, which is due to his sister. While they were enjoying, they talked about his sister and his sexual desire to her. The girl said she had taken a ghost away from him, so the memory about him and his sister will be brought back. While having sex, she said she loves him. (And you fap and i fap) After having sex, he found a lot of thingies are stuck at her body and she said they hurt. He asked her something he could do for her. So she asked him out on a date, to where she had killed Kiyohiro-kun.
I hadnt read ch 1 so ill just fap and erase the story from my head. Hahaa