The official report is that the deaths are from a mass suicide at the cult.
Gasai breaks in to cook dinner for the whole family. Amano's Mom likes her.
One of Mom's coworkers was in the cult and died. She'll be looking after their son for a few days.
The son is a diary user.
Fifth, Houjou Reisuke, begins his campaign of revenge against Amano and Gasai.
Amano tries to find his diary. Gasai takes a more direct route.
When he unleashes poison gas, Gasai becomes as interested in the antidote as the victory.
Luckily, stabbing gets her both.