Soapland

 

Not a specific brothel, rather a whole brothel industry in Japan, Soaplands can be found in any red light district and, oddly enough, offer what the name suggests. If you're feeling dirty in more than one way you can go in and get lathered up by a prostitute.

This type of service can cost as much as $1,000 so presumably you want to really roll around in some mud beforehand to make it worthwhile. The gist of the service is you get washed from head to toe while you sit in a special chair that lets your bits hang free so they can get a good grip on them.

According to Wikipedia, round two of the fun happens when your new friend for hire greases up her whole body and then just rubs herself all over your squeaky clean hide, which we imagine creates an effect something like trying to hug a fresh caught bass whilst naked.
After all this occurs, if you're not too bored or sleepy, apparently you can then engage in sex and, because you paid for a good washing and slip n' slide session it technically no longer fits Japan's definition of prostitution. In fact, based on what we know of Japan, it probably doesn't fit their definition of remotely kinky.