The Day I Became a God

Yota Narukami is a student focused only on his college entrance exams. During his last summer break of high school, he is approached by a girl named Hina who says she is the god of omniscience. She tells him that in thirty days, the world will end. At first Yota doesn't believe her, but after she demonstrates supernatural predictive abilities, he becomes convinced her power is genuine. Hina, meanwhile, decides for some reason to stay at his house, and they begin a tumultuous vacation facing the end of the world together.

Synopsis from Anime News Network