I thought up a porn doujin idea awhile back based on something that’s kind of common but got too into keeping the characters true to themselves that I ended up with an ending I didn’t like because someone would be sad.

All that being said it started as just ‘what if Takumi got blue balls syndrome and using his own hand doesn’t work so unless a girl gets him off he’ll be incapacitated and in immense pain’. Another common trope is escalation as eventually hands stop working so it keeps having to go further and further. I don’t see Nozomi or Tsubasa being cool with it and I see Kurara and Moko as being curious about boys but not going further than hands. And then Kako is out by default