How is it possible that in one of the world’s most wired nations, Japan, few people have heard of Mark Zuckerberg, co-founder of the social networking giant, Facebook? According to a New York Times report, this lack of recognition could have something to do with the fact that few in Japan actually use Facebook.

While there are currently two million Facebook users in Japan, that only represents 2 percent of the country’s online population, a sharp contrast to the 60 percent in the United States. Japanese users have flocked to other various social networking sites and game portals, including Gree, Mixi and Mobage-town. Each one of these has more than 20 million users and each platform offers a unique approach to connecting people online.

So why have these sites gained popularity while Facebook remains largely unnoticed? According to the New York Times, it has a lot to do with privacy. Internet users in Japan are fiercely private and the favored sites allow members to mask their identities – a deplete deviation from the real-name, over-sharing user approach on Facebook.

Shigenori Suzuki, a Tokyo-based analyst at Nielsen/NetRatings, told the Times that Facebook    faces a challenge in Japan. There are already powerful rivals, and then there’s the question of Japanese Web culture. Zuckerberg has promised to address the Japanese gap, but this is one challenge that will not be easy, especially given the advanced entry of sites like Mixi and Gree.Facebook may be eyeing the rapid uptake currently enjoyed by Twitter in Japan. The micro-service appears to be catching on with a speed Facebook would envy. Twitter has enjoyed a surge in popularity as a result of a partnership with Digital Garage, a local Internet and mobile services company. Of course, Twitter has the advantage in that it does not require users to reveal their identities.

Not to be outdone, Facebook has stepped up its efforts to tailor its service specifically to the Japanese market. Volunteers translate the site for free and the company opened a Tokyo office in February to customize the site for Japan. For example, the Japanese version of the site allows users to display their blood types, which is considered an important personality trait in that culture.

There are some who have complained that Facebook’s Japanese-language site is awkward to use. And, there are many others who see very little reason to switch from their preferred platform. Mixi users, for example, enjoy their anonymity and are suspicious of the “openness” of Facebook.

In fact, a survey of 2,130 Japanese mobile Web users conducted by the Tokyo-based MMD Laboratory found that 89 percent of respondents were reluctant to disclose their real names on the Web. Another survey completed by Microsoft in Japan found that more than half of respondents said that none of their acquaintances on social networks was a close friend.

Mixi allows users to sign up with pseudonyms and allows them to fine-tune controls over who can see posts and other uploads. Facebook insists that users adhere to its real-name policy. Can Facebook find the success it needs in Japan by demanding users conform to its culture instead of the other way around? This may be a “wait and see” proposition.