Since a certain day on which a number of dungeons suddenly appeared throughout the world, mankind ushered in the “dungeon age.” Through despicable assault measures, human players had killed the boss “Adesaile” of an abyss-tier instance dungeon. He unwillingly reincarnated into the body of a pathetic waste of a player, then the personal BOSS system became active. With the special capacity for becoming dungeon master through the system, his path of revenge begins.