30 years ago, the balance of reality on earth was shattered. Portals, passages connecting the earth and other worlds are created and Monsters, 1/3 invading creatures appear through the Portals. Nothing could stand against them despite military might. In the great chaos, several people appeared who could stop the monsters. They are called Players. Players power are given by the System to maintain the original balance of the world. After 7 years of The Calamity Days, Towers emerged which was the main branch of Portals and Dungeons and it was at that time that the figure of a stronger player was Ranker, appear.

And I, Kim Suho, the first SS-Class Ranker in Korea, was betrayed and killed by my own party members?