The city is actually just a vast swampland at the time (which is why Disney was able to buy so much land to make Disney World as big as they wanted, and other huge theme parks were built there).
Big Fancy House: Haruka's summer island house; not only the house itself is vast and luxurious, its bathroom is even more over-the-top; to the point the main protagonist wonders what's the purpose of building such a huge bathroom, and comments that he'll never understand rich people.