"Petite fuzoku girls in Nishikawaguchi" — some people hear that and know exactly what it means, and some don't.
I'm 42 and still working this world on the ground, so I'll lay it out from a real-world perspective.
Why this topic matters
A surprising amount of information about fuzoku (Japan's licensed adult-entertainment business) is poorly organized. Beginners especially tend to end up not even knowing where to start looking.
What it actually comes down to
In one line: "whether you know it or not changes the quality of the experience."
What's written here is the essence of the knowledge I've built over 20 years.
In closing
If you've got questions on this topic, hit the comments or social media. And go check out First Class Ruby while you're at it.