The Future Diary OVA

Yukiteru Amano is used to staying on the sidelines of school life. He doesn't try to make friends, rarely takes part in group activities and prefers to observe the people around him, recording his thoughts and everything that happens each day in his cell phone diary. In his imagination he has a special companion: Deus Ex Machina, the mysterious god of time and space. Yukiteru believes Deus is just an imaginary friend, until one day he discovers that the god truly exists and has decided to grant him an unusual gift.

Yukiteru's phone diary begins to show entries about the future. At first this seems like a real advantage, letting him predict what will happen and avoid trouble, but soon the diary reveals something far more terrifying: an entry foretelling his own death. His classmate Yuno Gasai behaves especially unexpectedly. She seems like a model student and is always near Yukiteru, but it turns out she keeps a future diary of her own, filled with predictions about him. Yukiteru soon realizes his diary is only one of several, and that Deus has created a survival game for their owners.