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.
Hinata is Tenth's daughter and has his diary. She takes Amano's diary at knifepoint.
Aru Akise, another classmate, fakes having a diary and engages Hinata in a high stakes bet. Can he beat future information? Yes. Lying to Amano puts false information in the diary.
Yuno Gasai, one of Amano's classmates, catches his eye. She's left behind a clay figure of Murmur.
How can she see what's only in his head?
Worse, his diary says he'll be caught and killed on the way home. Dead End.