In a world ruled by the enigmatic Tower, where climbers gain power through classes, skills, and contracts with cosmic sponsors, a boy without any of them dares to climb. Ryu Jin-Seok, raised in secret and trained by a vanished legend, enters the Tower not for glory—but to uncover the truth behind his grandfather’s disappearance. But within him awakens a strange, hidden system unlike anything the Tower has ever seen. As ancient powers stir and factions move behind the scenes, Jin-Seok must face deadly trials, broken champions, and the weight of a legacy he never chose—one that may change the Tower forever.