The Machiavellian ruler in Terry Pratchett’s "Discworld" novels, Lord Vetinari, once compared taxation to dairy farming. "The task,” he said, "is to extract the maximum amount of milk with the minimum of moo.”

Japan’s tax agency is learning this lesson the hard way. It’s found itself with an unexpectedly large amount of moo after a seemingly innocent campaign to support local industry went viral. The problem was that the sector in question was the alcohol business; the agency is soliciting open-ended ideas from young people for ways to help revitalize the nation’s liquor trade, amid a decline in drinking among younger people.

Tax revenue from alcohol has been falling for years in Japan as the population ages and a younger generation, fewer in number, shies away from the hard-drinking habits of the past, like once-obligatory post-work binges. That’s bad news not just for Japan’s tax coffers, but also listed makers of beers and spirits, the 1,400 sake breweries and hundreds of other makers of shōchū, whisky, craft beer and gin.