Stand by Hachiko statue just outside Shibuya station from 6 in evening. Look polite and smile at your host nation,s fairer sex. You could well become lucky with an amateur. If not the fleshpots on Dogenzaka await. Good fortune and let us know how you get on
With respect, I really don't think it's that simple. Can you say otherwise from personal experience and maybe give us a blow by blow?
For a non-Japanese speaking tourist, or even someone with very basic Japanese, I've found such ploys rather poor. The Japanese are not very trusting of foreigners – partly as we are so ignorant of their cultural norms and they don't want to offend us and so they keep many things 'Japanese only'. I only cracked the semi-impermeable wall by teaming up with a bi-lingual Singapore man who showed me where to go and how to 'persist gently'. I'm sorry I don't have addresses. So many places look exactly the same from outside! But if I could stay there for six months, friends there assured me "I would find a Japanese girlfriend".
If money's no object you can pay high odds through agencies or middlemen of course – not something I'm prepared to do. I've been three times and it is the only country I've ever resorted to a 'guide'. And that's after several months preparation learning beginner's Japanese, which I am still rather poor at, but at least I think I can tell the difference between a Korean and a Japanese prostitute – the latter are much more expensive of course!