Allthe world Japan and other countries have been destroyed because Monsters emerged from the Dungeon and several Races of demons,elves and Dwarves appeared and they mixed their lives with humans and fought together conquering Dungeons and strong people founded Adventure Guilds to for those who want to be adventurers and Dungeons graded from Rank D to S which is almost impossible and choose your race:Demon,High Elf, Dwarf, Beastman or human and choose what your job is as Adventurer or guildmaster