Of course they're all rich and worldly, they're royalty after all. It is possible that Kenji's company is located in or near Azubu, and was able to buy the property for the Tsukinos without giving him that large of a salary. A lot of houses are bought outright by employers like this for sarariman in Japan -- the real estate market there is really different, including the near lack of a market for "used" houses. But I'd say that upper middle class is the low end of the possibilities for Usagi, considering how much coin she spends at Crown Arcade.
But as for Pippi Ponytail, her parents must have left her a bag of gold.
-- ∇×V
But as for Pippi Ponytail, her parents must have left her a bag of gold.
-- ∇×V