The "one-coin theory" is a hallowed principle of retailing in Japan, the idea being that if your product can be purchased with one coin, people are more willing to buy it. This principle was formulated through Japan's extensive vending machine business, in particular vending machines that sold beverages. Until the mid-90s, 100-yen was the upper limit for all canned beverages sold in vending machines since it was considered a kind of psychological barrier. Most vending machines are owned by beverage makers, and no one wanted to be the guy who increased their prices first, even though material costs had been rising for years. If one was going to do it, they all should, and eventually they did. After a short period of sluggish sales, profitability eventually returned and there have been regular rises in prices ever since. The standard VM price is ¥120 for canned drinks and ¥130-¥150 for drinks in larger PET bottles.

But in the past few years, there's been a marked reversal. Independent vending machine operators have bucked the big manufacturers like Kirin, Suntory, Asahi, Pokka and Dydo by selling their products below the retail prices these manufacturers dictate. The trend has seen prices not only drop back to the one-coin level, but even further. Wex, a VM operator out of Osaka, sells Suntory, Pokka and Kirin products for ¥100, as well as its own private brand of canned coffee called Two Down for only ¥80, all in their own vending machines, and the big manufacturers are seriously ticked off.