Social gaming site DeNA may be big in Japan, but can it make it in the US? The WSJ.com has an interesting look at Japanese mobile-only service DeNA now trying to crack America. In Japan, the two-year old Tokyo start-up—which gives games away for free and earns revenues from avatars and advertising—has already amassed 11 million members to its main site Mobage Town. In September, its collection of games, chat rooms and avatars attracted some 15 billion page views.

Last month, it dropped $3 million to roll out pilot site MobMingle which offers English-speaking users rudimentary blogging, social networking and avatar services. It plans to launch a more complex site early next year that will also include games. Mobage Town, an apparent hit with young Japanese consumers, doesn’t charge for its games—which makes it stand out as most gaming providers in Japan do. What they ask for in exchange is for users to first sign up to its social networking service and to create an online avatar of themselves—which means they have “instant access” to user demographics. This allows programmers to tweak the site for them, and to sell virtual products for their avatars. Clothes, furniture, real estate, for example, sell up to several dollars a piece. Eighty percent of DeNA’s sales come from avatar-related purchases. Net profit at DeNA came in at $65.5 million for the year ended in March 2008, double from the year before.

Of course, there are several examples of mobile consumer practices or content services that caught on in Japan that never went anywhere outside the country, or have only gained modest traction. I-mode, mobile music, mobile TV and QR codes, for example, spring to mind. WSJ lists some of DeNa’s challenges—they point out that almost as many Japanese accessed the internet through their phones, as they did from computers last year. Americans are just beginning to surf the web on their mobiles. Phones in Japan are much fancier, while many American ones still don’t even come with Flash Lite (hello iPhone) and hence means phones can’t display animation. Mobile data is also cheaper in Japan. Plus, there’s the weak economy that may prompt cutbacks in mobile advertising.