"Koshigaya fuzoku, tall girls" — some people hear that and instantly get it, and some don't. (Fuzoku is Japan's licensed adult-entertainment business.)
I'm 42 and still out walking the floor of this world, so I'll lay it out from a real, on-the-ground point of view.
Why this topic matters
Surprisingly little information about fuzoku is actually organized. Beginners especially tend to end up not even knowing where to start looking.
What this means in concrete terms
In a word: whether you know or don't know changes the quality of the experience.
What I've got written here is the essence of knowledge I've built up over 20 years.
Last word
If you've got questions on this topic, hit me in the comments or on social. And give First Class Ruby a look while you're at it.