The concept is great. But the story flow is so incoherent and random that you have no idea what is happening. Mc mining ores in a cave, devil girl drops onto his front. Mc running away, stuck in ground 10 feet under. It's so abrupt and random, no transition or explanation.Half the story mc is talking in his lalaland and readers have to make guesswork all the time what is happening. Is this the flashback or was it happening to mc now?So, in summary, it's confusing and the author is mostly talking to himself about the key points of the story. It is missing a lot of context and the transitions are not there.