See, all millionaires ultimately want the same thing: something pretty and expensive that they can show off to all their friends and which they can get into a few times a day. Today, they'd just buy a luxury car. But back during the Edo period, they bought themselves a mistress. Now, mistresses were an integral though complex part of life in old-timey Japan. First of all, there were many kinds. Some resided in their own homes and had a bunch of sugar daddies that would visit her at different times. Or maybe sometimes at the same time. We guess some guys might've been into that. We don't judge. Plus, think of all the time the women saved on that. Other mistresses would go out and visit their patrons in their homes, basically the Little Caesars delivery of its time, right down to their slogan probably being "It's hot and it's ready." There was apparently even a kind of mistress that would visit a married man's house when his wife was out, often uninvited, and only left when she was compensated. We're just going to assume that that kind wasn't super popular. But the important thing is that, in most cases, being a mistress was an actual job, with actual signed contracts and everything.
Although we tend to have this idea of samurai Japan running on a Klingon system of everyone swearing on their honor etc., it was actually a super bureaucratic society. Damn near everything was done via contract, including some forms of prostitution, often carefully detailing obligations of both parties plus penalties for breaking the contract, etc. And just take a moment to think about some Japanese scribe having to write up a contract explaining just how many times a mistress had to spank her client a day and the exact measurements of her octopus costume. Not that there's anything wrong with that. We don't judge. In any case, it was this kind of litigious society that eventually helped create the Urine Gangs.