The Future Diary

Yukiteru Amano, a socially isolated high school student, uses his cellphone to write a diary while interacting with Deus Ex Machina and Murmur, who he initially believes are imaginary friends. Deus Ex Machina is later revealed to be the god of time and space, and he grants Yukiteru a "Random Diary" that displays highly descriptive future entries. This diary forces Yukiteru into a survival battle with 11 other holders of future diaries, with the last person standing becoming the new god of time and space. Yukiteru teams up with Yuno Gasai, who is also a diary holder, and initially acts as his protector due to her obsessive behavior.