Histoire
One day, countless dungeons suddenly appeared in the world, and humanity ushered in the "dungeon era". Adesalai, the boss of an abyss-level dungeon, was killed by human adventurers via despicable means. Vowing revenge, he was reincarnated as a weak adventurer, but he activated an exclusive Boss System. Using the system's cheating powers to conquer dungeons and becoming its master, he started on the road of revenge.
Synopsis via AniList (en anglais).
