Mirai Nikki

A high school sophomore, Amano Yukiteru, struggles to form friendships and views himself as an observer, documenting daily events in a phone diary. Suffering from loneliness, he imagines a companion named Deus Ex Machina, described as the ruler of time and space. Observing Yukiteru's distress, Deus grants him a power: his diary now records upcoming future events. Yukiteru is then required to take part in a competition, with the prize being the position of Deus' successor.