three-shop system; pachinko prize-exchange system
A legal workaround used by pachinko parlors in Japan: a player exchanges won balls for a 'special prize' at the parlor, then takes it to a separate, nominally independent shop to exchange for cash, thereby circumventing gambling laws.
Pachinko parlors provide cash through the three-shop system.
The three-shop system is known as a loophole in Japan's gambling regulations.
The game itself; 三店方式 is the prize-exchange system used by pachinko parlors.
General term for converting something into cash; 三店方式 is a specific method of doing so for pachinko prizes.
From 三 (three) + 店 (shop) + 方式 (system), referring to the three separate entities involved: the pachinko parlor, a prize-exchange shop, and a wholesaler.