Harukaze Reito, a retired top-ranked adventurer, wants nothing more than a peaceful life.But his quiet days are interrupted by the appearance of a broke and energetic gal-type girl, Hiiragi Karen, who asks:”Hey, Onii-san! Will you treat me to a meal?”Moved by her situation, Reito gives her a basic crash course in dungeon crawling.Thanks to his guidance, she clears her first dungeon and excitedly declares:”I did it, Master!”Now, Reito’s dreams of a laid-back retirement start to crumble…