Negattemonai Tsuihougo kara no Slow Life? ~Intai shita Hazu ga Nariyuki de Bishoujo Gal no Shishou ni Nattara naze ka Mechakucha Natsukareta~

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…