mirai nikki (未来日記, future diary) is a japanese anime and manga series written and illustrated by sakae esuno.

middle school student amano yukiteru has problem making friends. he thinks of himself as a bystander and will always write down everything he sees in a cell phone diary.

tormented by solitude, yukiteru interacts with his imaginary friends deus ex machina, the god of time and space, and muru muru, deus' servant. one day, deus grants yukiteru's cell phone the ability to record the future for the next 90 days. yukiteru is then forced to participate in a battle royale with eleven other people, each of whom also have a diary that can predict the future in some unique way.

the rules of the 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 deus' successor.