>>33572797 (OP)
Soaplands are the bathhouse brothels where you can meet the local prostitutes. However the vast majority don't serve gaijin, some may serve some non-japanese races but not others lol. They'll be a lot of choice in the red light district. You can approach the madam of the house in the lobby (called Mama-san) if you're interested (sometimes it's a guy) and ask if you're welcome to partake. If you're not they'll politely but firmly shoo you away. Don't take it personally, this is the accepted and expected way of operating.
The ones that do accept you will give you like a menu of girls to chose from. If it's an especially fancy place you'll be able to see the girls in person. You'll be expected to bathe before fucking, like using a pool in certain states.
Money up front is the norm. Don't haggle on price. It's usually about $100 an hour. Which is honestly pretty reasonable for a first world screw. If you want cheap as fuck try Thailand. It's like $30 for a high end there.
Tobita Sinchi in Osaka is a good district to start in.
Good luck getting your dick wet