Moves toward legalizing casinos in Japan have reignited a debate over the legal status of pachinko, with a potential new tax mooted for a $200 billion gaming industry that has existed for decades on the fringes of the law.

Pachinko, a slot-cum-pinball form of gambling, is a national obsession, with 1 in 6 Japanese playing the game, though that number is declining as younger generations prefer to play games on their mobile phones.

With past links to organized crime, pachinko is not classified as gambling, which is illegal in Japan. Instead it's treated as an amusement activity like arcades and hostess bars, and the operators of the parlors that are found in city streets across Japan pay no gaming tax.