Aiz Wallenstein is the Sword Princess, one of the best fighters from the most powerful group in all of Orario, Loki Familia . She's consumed by one goal: become stronger. Together with her familia, Aiz departs on quests to some of the deepest floors of the dungeon, exploring and fighting the dangerous monsters born below. But when one expedition goes terribly wrong, will Aiz be strong enough to save her familia, or has all her work been for naught...?