Armagedon

(Plot summary taken from MangaUpdates)
Hundreds of millions of years ago, highly-advanced beings looking to make a planet for themselves purposefully tampered with Earth's natural processes in order to create multi-cellular life. Watching the planet's evolution closely, they continued to help life evolve further in the hopes of having actual civilization develop.
It's now 1996 in Seoul, where Hyesong, a high-school student, struggles with the usual problems of youth. The only unusual thing about him is that he's been having the same apocalyptic nightmare for an entire month; in the dream he is an great fighter and genius tactician who faces off against a seemingly-unbeatable foe.
Are these dreams not really dreams? Does he really have a role to play in the cosmic balance of the universe? And is the new girl in his class really just a normal student?