At the end of the last summer vacation of high school, Youta Narukami spends his days preparing for the university entrance exams, when a young girl named Hina suddenly appears, proclaiming herself as the "god of omniscience." Youta is confused and does not believe Hina when she tells him "The world will end in 30 days." After witnessing Hina’s God-like predictive ability, Youta begins to believe her powers are real. Hina, who is innocent and childlike despite her supernatural powers, decides for some reason to stay at Youta’s home. Thus begins the start of their lively summer before the end of the world.

All thanks to the special ability that he developed, Yuu was able to cheat his way into a very prestigious high school. With his power, he thought nothing was going to stand in his way, until he met a mysterious girl named Nao Tomori and other students with special abilities just like him. It was the beginning to a new life.