There's a limit to the size of plot holes that I can ignore even in a comedy. To start off, it connects to another world, but he just wants to sell it at a low price to someone? What about the government or an organization to control this ridiculous gateway? The resources and everything else. The potential invasion of earth from that spot or people on earth to invade that place. You're telling me this is nothing big?
Also, this guy goes into the dungeon with but a pickaxe and helmet as if he's going to mine some ores while knowing that monsters will show up? Oh, and perhaps the biggest fallacy of all, he said her thighs were unpleasant just because they had some piss on them. A true japanese man would call that a reward.
I can't see this going anywhere good, but I'll try another two chapters as usual.