[Light Novel] Mirai Nikki Vol.1

Yukiteru "Yuki" Amano is a loner who never really interacts with people and prefers writing a diary on his cell phone with his imaginary friends Deus Ex Machina, the God of Time and Space, and Muru Muru, Deus's servant. One day, Deus gives Yuki a special diary, mentioning something about a game. Yuki pays it no mind until he discovers that his new diary has entries in it spanning the next 90 days--entries about the future that come true with unnerving accuracy. Deus, the not-so-imaginary God of Time and Space, then forces Yuki to participate in a battle royal with eleven other people, each of whom also have a diary that can predict the future in some unique way. The rules of this "Diary Game" are simple: before the world ends on day 90, the contestants must find and kill all the other contestants, and the last one standing will become the new God of Time and Space.