Wait could the old hag be Momoyo? Mining could sound like rhythmic drum beats. She has grey hair and would have a basket to, say, sell precious metals to the kappas (or a human found their way into the mine and she's just disposing of the body). Aya being weirdly hesitant to say what she wrote is true is so strange to me, I guess the people calling her a sham reporter are starting to get to her.