Okay so one question: who would be the most attractive among the girls if we imagine what they'd look like in real life?
Disregarding all of the human trafficking theories, nationality will have nothing to do with the criteria. Just basically, who
would have the most attractive features.
Setting aside the side characters cause Niki would be the winner by default. I had a thing going on for Tsuneyo for a while so I think she's my bet for now.
It'd likely depend on what one finds attractive.
Imo though, Touka would probably be the winner overall if we take a generalized approach. She's blessed in many ways. Including being rich as hell, being busty, being healthy and clean, being highly intelligent, being trained in combat and business, being cultured, and being an actually good person, etc. Her only real issues is that she's too compassionate, and she is inexperienced when it comes to common life, albeit those can be seen as attractive qualities anyway.
Touka was more or less virtually bred and raised to be safely attractive. Not to say the other girls aren't attractive, but I think most of them have something that would make them seem less attractive on paper to every other person. Whether it's simply that they are poor, need medications, have less prominent bodies, or have more prominent styles.
I also think if we include the side characters, Touka would still probably win. Niki has a simp club, but I'm sure there are plenty of haters out there as well. She's not exactly seen as a real person and if she suddenly is, she'd become way less popular, if not considered obsolete. She's also nearly in her 30s, which is apparently unattractive for Women. Her hair, style, personality, etc could also be deal breakers.