"There goes a brave man. Whether he comes out alive or not, this will surely be remembered as one of the most courageous and gallant acts in sexual history."
The preceding underwent a slight modification ... likely someone else out there will either recognize or identify the original source material.
All I could think was how that village could bottle the water and sell it like Spanish fly or the ultimate Viagra and that the world would be a better place...
I'm not completely sure which branch(es) of real-world science might apply here, but could this be a case where Nature itself acts as the ultimate wingman to (so-to-say) get the nation of Japan to start replenishing its (supposedly) dwindling population ... by making people horny due to (a-hem) naturally-occurring volcanic emissions?
And if that is the case, the system still needs further (a-hem, again) work as, unless the Japanese themselves find a way, anal sex (as well repeatedly applied to female protagonist) won't result in pregnancy or an eventual population increase.
...Such a missed opportunity for a ♨ mark in the title.
But man, they kind of just...lumbered towards her and held her down without even saying a word. They're like zombies looking for flesh...Except they're alive, and looking for flesh in a...different sense.
Heh, when mother nature steps in and makes a volcano making an entire town have one big orgy.
Great ending though! Yes...Go and 'help' them, that's what a responsible human being would so very naturally do.
That sucks.