Dungeon no Naka no Hito

Clay was taught by her father to be a skilled thief. After he vanished three years ago, she has used her abilities to search for him in a dungeon inhabited by goblins, a Minotaur, and various other threats. When she ventures farther into the dungeon than anyone before her, she encounters the dungeon's caretaker. To her surprise, she is offered a position on the staff. Her new role involves learning the dungeon's operations and uncovering its hidden secrets from within.