Amano's friends team up with Ninth to take out Eleventh's supercomputers.
Eleventh's diary, The Watcher, shows him what everyone else's diaries say.
In fact, Eleventh was the one to suggest Future Dairies as a part of the death game in the first place.
Ninth figures it out.
By editing false information into their diaries, they can fool Eleventh.
But he's one step ahead. His secretary has a diary that records his actions. That one is known to be reliable.
Ninth loses a hand in an explosion. Nishijima is shot dead. Amano's friends are captured.