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.
By the way, Third was the homeroom teacher.
The Ninth keeper, Uryuu Minene, comes to the school to follow up. She has placed remote detonating bombs around the school to flush out Amano.
The head cop tracking her, Fourth, is also a Future Diary user.