Mazui Subs

Amano Yukiteru, is a middle school boy with no friends, who thinks of himself as an observer and writes everything he sees in his cell phone diary. His imaginary friend Deus Ex Machina, who is apparently the Lord of Time & Space, changes his diary to record events that will happen in the future. Yukiteru is then forced to participate in a game against other diary owners in which the winner will become Deus' successor.

Based on the manga by Esuno Sakae.