Pachinko is a form of disguised gambling; it was devised in Nagoya just after World War II and is based on the American pinball machine. A good place to go if you want to experience pachinko firsthand is Maruhan Pachinko Tower in Shibuya. Here, each floor has a different theme, and there are special seats for couples.
Winnings from pachinko are generally exchanged for goods – brand-name goods in upscale areas – or for money, but the money exchange has to be done outside the premises to remain within the law, through a hole in the wall. This is because gambling for money is illegal in Japan, except for certain approved (and unsurprisingly highly popular) activities such as horse-racing, powerboat racing, bicycle racing, and major lotteries.
More often than not, however, a blind eye is turned by the Japanese authorities to the ways in which people choose to indulge in gambling. Mahjong is played in private clubs and homes, for example. Some hostess clubs offer gambling in addition to their other services, as long as it is not for money.