Angae Sogui Goemul

A thick layer of mist shrouds the world and turns people into zombie-like monsters. Without knowing its cause or the solution, the only way out is to sneak into the capital city built for the privileged. While struggling for survival, Hayeon, a talented biologist, finds out that his crush Myung Woon has something to do with the virus...
(Source: Pocket Comics)
Notes: The chapter count includes a prologue and 16 side stories. The side stories contain mature scenes.