It is the familiar background music of every Japanese shopping street: a cacophony of mechanical bleeps and rattles, disgorged along with a plume of cigarette smoke each time the doors of a pachinko parlour open to admit another punter.

Yet the archetypal salaryman pastime is dying, in spite of its apparent ubiquity. Even as Japan looks ahead to its first western-style casinos, pachinko, the modified version of pinball played since the 1930s - itself a quasi-legal form of gambling - has been all but abandoned by younger Japanese.

Data from a Japanese research group show that the number of players has fallen by two-thirds over the past 20 years to 11m in 2013. Just one in six men in their 20s now plays, down from half in 1995. For men under 20, the number is just one in 50.

The decline of pachinko, once so popular that a hit song from the mid-1990s exhorted addicts, "Get back to work! Your wife and kids are crying!", has been mirrored in Japan's other legal forms of gambling. Income at horse, boat and bicycle racing venues has fallen steadily for the past two decades.