pachinko is basically gambling based almost completly on pure luck. you shoot bearings and if they get into special places on the board, you get more ball bearings. but since gambling is illegal, you exchange the balls for prizes like tickets in an arcade....
but there's this seemingly useless fake gold coin you can ask for as a prize. somewhere outside but nearby the pachinko place you can exchange the coins for real cash. kinda like a loophole around the gambling issue