That's call sumata 素股
https://en.wikipedia.org/wiki/Types_of_prostitution_in_modern_Japan#Sumata
Wikipedia tell you all you need to know in like 100 words.
I don't know guys, my top 1-2-3 (very close) orgasm is in a vagina, in a rectum, in a mouth, all without condom of course. A distant 4th is my own right hand. Number 5... I don't know. If a girl is with me but for whatever reason I can't fuck one of her orifice, I almost prefer to masturbate myself over having her do something, handjob, paizuri, sumata for me. Maybe I'd fuck her thighs doggie style while squeezing her tits... That's probably the least disappointing option.
I think I just want to have my cock inside a "full enclosure". Pressure and rubbing from 360 degrees. The description
@uguptas sure yes that can probably get my rocks off, but there's no rubbing between my belly and my cock. I can't imagine it's better than vagina penetration or my own hand masturbation.
I have never experienced sumata, either by a consent partner or a paid service provider. So maybe I just never had met a skilled practitioner.