I've had a story bit stuck in my head for ages. This story option might appear if you've romanced a certain number of girls, or reached a certain level.
Pay Debt
Elena is shocked as you hand her a massive bag of eros.
"Oh my! Y-You actually paid it all off?! Congratulations! I'm guessing you're planning on leaving Lucidia then?"
Stay here. | Leave Lucidia | This is all a scam, right?
"A scam?! W-Whatever do you mean? "
"A million eros? I've only seen a few adventurers with even a 10th that sum. And I'll bet there is no Demon Queen, or at least not one you ever intend us to defeat. All of this is just to get us to feed the monster girls."
Elena slumps in defeat, her eyes glazing over. "Yeah, that's all more or less right. Great, just great. So you are leaving? You have no idea how much paperwork it will take to explain why our quotas dropped so much."
Stay here. | Leave Lucidia
"Naw, you get your wish. Since you were honest, I'm staying. In fact, could you help me build a house here?"
Elena's eyes light up, as she exclaims, "Absolutely! Thank you, thank you!" Elena smirks mischievously. "But it'll cost no less than... 3 million eros!"
You then start a quest where you can leverage your romance with various girls and build a house near the Forest Dungeon, in the mountains near the Will-Power Temple, or maybe in the capital city. You can then pay Elly to make portals linking your house to girls you've romanced, so that, for example, Trisha would have her Inn in the forest, and a magical door that would instantly take her to her room in your house, effectively letting you visit any girl at any time. And maybe like cosmetic decorations for the house or something?
Aaaand to pay this insane amount of eros, you'd get a new bonus for feeding monster girls. Basically, you get more eros if you not only make a girl cum, but also feed cum to any girl with the Semen Eater perk. So this would be a new challenge, if you're fighting an imp den, you can't just spam mass seduction, you actually have to cum in each girl at least once. Which would mean extra abilities that would increase your lust and decrease damage temporarily, or maybe for one move. Maybe "Selfish Thrust" or something.
And yes I've thought about making this as a mod but haven't done it yet