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.

When he wakes the next day, Amano sees that his diary has already been entered. With surprisingly confirmable details.

Deus tells him that the diary is his future, with that drawback: if it is destroyed, he will die.

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.

Gasai knows this, because she also has a Future Diary. And she's been stalking Amano and writing his movements.

But that does mean she can help him avoid Third, the other diary user and serial killer who is after him right now.

They lure Third to the roof of the building, and when he draws his phone to check where they are, Amano punctures it with a thrown dart, killing him.

Deus brings the eleven remaining competitors into a vision and explains the rules: They must discover and kill each other.

He names Amanao, First. No doubt the top contender if he could pull off a miracle like that.

It was actually Gasai's doing, but Amano has the target on his head.

Don't worry, Gasai will protect him, with all the force that a Yandere girlfriend can muster. (Worry.)

The winner of the contest will get Deus' cosmic powers!

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.

Ninth protects her phone by putting her eye in harms' way instead. She escapes.

Fourth is not interested in godhood, but wants to stop the murders. He proposes a team-up between himself, Amano, and Gasai.

Each person's diary shows different details based on how they write.

Fourth's name is Kurusu Keigo.

(Gasai is Second.)

Amano and Gasai go to an amusement park together... to lure out the other Diary keepers. Yeah, that's it.

Ninth escapes, but is captured by another Diary keeper.

Amano opens a locked door at Gasai's house and is shocked.

Why does she have dead bodies (mummies?) in her spare room?

Amano flees, but it's not like he can really get away. She knows everything he does, after all.

His opening of this door changes everyone's future.

Ninth has been captured by a cult. The leader is Sixth, Kasugano Tsubaki.

She has a Dead End showing in her diary. She wants to trade Ninth for Amano's help avoiding it. He's dodged two already.

The problem is that Sixth's diary shows what her cult does...

... and they've been hypnotised by Twelfth. Information about the future is worthless if it's false.

Gasai figures it out, but also believes Sixth is poisoning Amano against her.

She give him an ultimatum: come with me and live, or stay with Sixth and die.

Obviously, because the bad guys are after Sixth. This isn't her threat.

Twelfth, Hirasaka Yomotsu, is insane. He thinks he is a super hero.

Gasai dispatches him.

But it's a double cross! With Twelfth gone, the cult is un-hypnotised, and Sixth turns on them.

Gasai pushes Amano out of harms way, but Sixth orders her cultists to gang-rape her while broadcasting it over the loudspeaker to draw him back out.

Even though Gasai is crazy, Amano won't stand for this, and he kills Sixth by darting her diary.

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.