Okay, I'll concede that the term
Flower and Willow World refers to Geisha and not to prostitution.

However, there were indeed brothels in Japan which did not masquerade as either teahouses or inns or under any other euphemistic appellation. The Yoshiwara Yuwaku and Shimabara districts referenced in the Wiki article were
nothing but wall to wall brothels. Brothels have existed in Japan since time immemorial and still do.
This is a high class outfit we have here; instead of putting a brothel in every city the
Flower and Willow wonder can put a Geisha House in every city. Of course if you would rather have brothels we can change the name to the "Nightless City" wonder. There is an excellent book about the Yoshiwara titled,
The Nightless City or a History of the Yoshiwara Yuwaku. There are also two excellent movies which examine the issue of prostitution in Japan from opposite ends of the time spectrum. They are
The Life of Oharu and
Street of Shame. Both are considered to be classics.
Tak your comments on the space race have piqued my interest. Your assignment is to determine five elements of governance which Tokugawa Ieyasu divised to control the Daimyo following his assumption of the Shogunate. You already have some of them.
P.S.
Sankin Kotai