@quagzlor
The parable of the north wind and the sun describes how the north wind and the sun were competing on getting a traveler to remove his hood.
The north wind forcefully tried to remove the hood by blowing at the traveler, which was an attempt in futility as the traveler simply clutched his hood tighter.
The sun on the other hand made it a bit warmer, which persuaded the traveler to remove his hood.
The joke here is that like the guy, pulling off her clothes is an attempt in futility. But going into the kotatsu himself (while naked) he made it a bit too
hot inside (if you know what i mean). I believe there was a bit of implied wordplay in there.