Affair Bureau

I've seen mahjong parorls all over Japan. They seem to run the gamut from seedy yakuza haunts to respectable family entertainment places along with manga/internet cafes.What I want to know are three things. First, when you go there, do you go with your friends and get a table so you can play together, or is it like a casino/card room where you go to find a game with random people?Second, how do these places make money? Do they charge per hour for your seat and try to sell you food and drinks? Do some of them take a cut of the bets like card rooms?Which leads me to the third question. Gambling is illegal in Japan, yet mahjong parorls operate out in the open. Obviously nobody plays mahjong just for fun any more than they would play poker. So how do the players handle the exchange of money without attracting unwanted attention?