Japan has dislodged the U.S. to become the world's top app spender as consumers clicked more and more on their smartphones for just about anything to feed their requirements, from train schedules to games to fancy emoticons.

"Japanese are accustomed to spending money on mobile phones," Hiroshi Naya from Tokyo-based Ichiyoshi Research Institute Inc told Bloomberg. "If you see revenue per user for companies like GungHo, which distribute apps globally, Japanese users spend more than the rest of the world."

According to the App Annie Japan Spotlight report, Japan not only has overtaken the U.S. for app store revenue, it likewise shows no signs of abating in its growth.

As of end October, Japan's smartphone users spent almost 2.5 times the amount of money on apps compared to U.S. smartphone user counterparts in the same month. Compared to a year ago. U.S. app users were still lording it over, spending a third more on apps than users in Japan.

The rising popularity of games including GungHo Online Entertainment Inc.'s "Puzzle & Dragons" helped spur revenue in Japan to surge more than triple from a year ago, researcher App Annie added.

Downloads further jacked up after the country's largest mobile-phone operator, NTT Docomo Inc, began selling Apple's iPhone in September.

Free apps dominated Japan's list of top 40 highest-grossing apps. Games were the dominant factor. Smartphone users in Japan spent 400 per cent more on games in the past year, according to Quartz.

Compared with 28 per cent a year ago, Japanese consumers have quickly adopted to using the smartphones. About 42 per cent of the population now use the device.

The report further said Japan's smartphone usage will expand in 2014 to 62 per cent, possibly overtaking the 50 per cent penetration rate forecast for the U.S.

"The adoption of smartphones is much faster than what we expected," Peter Warman, chief executive at Amsterdam-based game data research firm Newzoo BV, said. "It's fueling further growth."