Episode 3 was really good but I admit I was confused. This is my understanding:
1) Yukina was lonely and convinced herself Masayuki was being abused when he wasn't.
2) Yukina's mother was mentally ill and started harassing Masayuki's mother out of jealousy. She sent her the hate mail with the crushed cockroaches and even attacked her cutting her head.
3) Masayuki set fire to the apartment because he thought Yukina needed to be saved from her mother. He ended up killing his mother as well by accident and blamed Yukina.
4) When Masayuki ran into Yukina when they were older, it caused him to have a mental breakdown and go on the killing spree.
1) Yukina was lonely and convinced herself Masayuki was being abused when he wasn't.
2) Yukina's mother was mentally ill and started harassing Masayuki's mother out of jealousy. She sent her the hate mail with the crushed cockroaches and even attacked her cutting her head.
3) Masayuki set fire to the apartment because he thought Yukina needed to be saved from her mother. He ended up killing his mother as well by accident and blamed Yukina.
4) When Masayuki ran into Yukina when they were older, it caused him to have a mental breakdown and go on the killing spree.
Did I miss anything?