We start with a grizzly murder.
Cut from there to school. Yukiteru Amano, our MC calls himself an observer. He doesn't participate in things, but obsessively keeps track of everything that happens on a diary in his cell phone.
He has no real friends, but rather, imaginary ones.
Like Deus Ex Machina, God of space and time. And Murmur, his servant.
Deus asks if he wants to change his life, and sends him a message that contains the future. This will be a new game.
Meanwhile, the serial killer continues to stalk people who are out alone after dark.