قسمت 4: جنون کی‌ایشی شدت می‌گیرد و او رنا و میون را می‌کشد، سپس به خودکشی می‌پردازد.

4

Rena pays Keiichi a visit, attempting to bring him dinner, and begins acting strangely, intimating that she has been monitoring him inside his home, prompting Keiichi to succumb to his paranoia and slam his front door on her hand. Distressed by Keiichi's behavior, Mion attempts to apologize for keeping so many secrets about Hinamizawa from him, but he coldly rebuffs her. Later, Keiichi is being followed by Rena, carrying a machete. He demands to know who caused all the murders and disappearances; Rena simply replies that it is all the work of Oyashiro. Keiichi escapes from Rena and finds himself being chased by a mysterious group of men, who knock him out. When he awakens in his room, he is attacked by Rena and Mion, who attempt to inject him with a syringe. In self-defense, Keiichi beats Rena and Mion to death with Satoshi's bat. He calls Oishi and tells him the murders were caused by Oyashiro, and then Keiichi, who is sure that Oyashiro is behind him, claws out his own throat. The next day, Keiichi is found dead. The police also find the bodies of Mion and Rena, and they find out that Keiichi was the one who killed them. The syringe that Mion used, which Keiichi attmepted to hide in a wall clock, has also been removed. (Source: Wikipedia)