I came out of the black screen with MTool, and you were in the wrong place, I guess your save got corrupted for some reason. Or the dev has a sneaky bug that triggers under certain conditions, but this is unlikely, because only you reported this problem. Files can get corrupt when you're saving, check your drive for integrity, just in case. You can use CrystalDiskInfo or something.
Maybe, when you create a game with many variables at play, you have to keep track of them and the logic behind it. This particular issue you have is hard to track and happens under very specific conditions. It affects only you so far, and I'm only the translator. I have no obligation, not enough time to spare, or enough reasons to fix it. Sorry.