Mirai Nikki (TV)
The Future Diary
Yukiteru Amano is a timid middle schooler who keeps track of his day-to-day activities by writing them on his phone. He doesn't have any friends at school, but he's often seen talking to his "imaginary" friends Deus Ex Machina and Mur Mur.
One day, he notices that his phone is predicting future events. At first, he thinks it's a coincidence, but he soon realizes that the predictions are accurate. He uses this to his advantage throughout the day. When he and his classmate Yuno Gasai get back home, Deus Ex Machina explains that they have been chosen to compete in a survival game, in which the winner will become the new god of time and space. Yukiteru and Yuno have to use their phones - now called "Future Diaries" - to survive the game.