Kenji Kasahara, founder and president of mixi, Inc., poses at his Tokyo office. The notebook PC beside him displays the Web site of the popular social networking service his company operates.

The 42-year-old expectant mother has found new friends, with whom she shares her concerns and most-private thoughts, recording the events of the days in her online diary. Takai feels she has personally greatly benefited from the interaction on the Web site. "I believe I have developed more because of it," she says.

Social network services focus on the building and the verification of social networks for any number of purposes. Most social networking services are open to the public, others are by invitation only. Many sites also serve as blog-hosting services.

When Takai learned her baby was breech, which could necessitate her having to have a Caesarean, Takai's cyber-friends were there with their support. "I, too, had a baby that was breech," wrote one person. "But I kept doing turning exercises, and, at the last minute, the baby changed position."

Others express their concern, remaining upbeat and optimistic and cheer her on. "It's nothing unusual. Don't worry. The doctors will take care of you and your baby."

Mixi members create profiles on the site and invite friends or family members to join. Others, in turn, bring in their friends, and may join with their friends' friends. Takai is typical in that her cyber-friends are much like her, women of similar age who have borne children or plan to.

According to Kenji Kasahara, president and founder of mixi, Inc., members feel they are communicating with real people though the service is a cyber-world. Members agree. Some say that they reveal themselves, to a certain extent, in profiles and diaries and communities they belong to give each other a feeling being true to real life.

Kasahara sees mixi as a communication tool whereby "people can enrich their lives . . . and strengthen current friendships."

Takai, on leave from her position as a professor at a Japanese business school, found mixi was just what she needed. After taking leave, she has kept busy with domestic chores and writing research papers, but doesn't want to isolate herself from others. "After I write for three hours, I log in to mixi.jp, write in my diary, read what others have written and spend 15 minutes or so replying," she says.

The Tokyo-based mixi was first introduced about two years ago. It was initially popular among university students and IT professionals. Mixi spent little on advertising; its marketing was predominately done word of mouth, in sharp contrast to Web sites that emerged in the late 1990s. Early sites relied on heavy cash investments for content and marketing.

Mixi now claims more than 4.5 million users who have registered since its February 2004 launch. According to the company, about 70 percent of its members log in at least every three days. It is Japan's third-most-visited Web site and ranks No. 41 worldwide, according to Alexa.com, which traces and ranks global Web traffic. The word "mixi" has become a catchword for other similar sites and is often used as a verb.

Mixi's basic service is free, but a recent revenue-producing premium service for about 300 yen a month, allows members to expand their capacity for photos and diaries, along with other options. In addition, mixi sells online advertising and provides financial incentives for purchasing goods and services through affiliates on the Web site.

Mixi's more than 730,000 "communities" have also surely helped boost its popularity. Members can easily find places to talk about anything and everything, with others who will surely understand.

Topics that are still considered taboo or sensitive, or interests that some feel would be embarrassing to talk about with others, can easily be discussed on mixi. The invitation-only aspect is a feature that appeals to the more timid Japanese.

Yahoo Japan Corp., operating Japan's most-visited Web portal and Rakuten Inc., Japan's major online retailer, recently announced their own social networking services in an effort to compete with mixi's phenomenal success.

At the end of last year, there were over 300 major social network services worldwide, including the huge MySpace (over 69 million users), Friendster and LiveJournal.

The number of people, like Takai, taking advantage of such sites has mushroomed in Japan as social networking services are increasingly seen as a means to enrich one's life.

According to the Ministry of Internal Affairs and Communications, which compiles data reported by 21 companies, including mixi, Inc. and other social networking services offered nationwide, the number of registered users of such services was just over 7 million at the end of last March.

Information technologies, at first, enabled individuals to bring a one-way flood of information into their lives. In the mid-'90s, Japanese took to building home pages as a forum, albeit one-sided, for expressing themselves. In the late 1990s, the boom in text-messaging from cell phones became the way for Japanese to connect to family and friends, especially among those in their early 20s.

In recent years, however, blogs and social networking services have become increasingly bi-directional and capable of accommodating more open dialogue. This is what has captured millions of Internet users with a desire to be seen, heard and understood by others. The desire for such a forum was long there, says Masataka Yoshikawa, a research director of Hakuhodo Institute of Life and Living, a major think tank tracing lifestyles in Japan. The new technology has merely met the need.

In Japan particularly, Yoshikawa explains, the communication style has found a perfect match with the self-centered, rather contradictory mind-set of youth. "Teens and people in their early 20s don't want to be disturbed by others, but they strongly want to be connected with them," he said.

He says that the burgeoning numbers indicate that users have learned how to have such sites cater to their lifestyles and explains their popularity among Japanese in particular.

More than 20 percent of Japanese post their messages on blogs, keep diaries on such sites as mixi or update their home pages at least once a week, Yoshikawa says, citing Hakuhodo Institute research.

"What people write," he says, "is not necessarily serious or deep. People usually don't even expect others to respond to their messages. It's why others can respond in a very casual manner," he says. "It's because of this that people may gain a new perspective on things or learn some new information. They may be motivated to learn so they can write about things in their diaries and blogs. As a result, their lives may be enriched."

This, Yoshikawa points out, tends to be slightly different from the norm in other countries. In the United States people tend to use the services for practical purposes, such as finding employment, cars, and friends. Japanese tend to use such communication media merely as a ways to express themselves or share their experiences and daily lives with others.

Mixi or other Japanese network services are more general and wide-ranging than American services, which tend to specialize, says Bob Witeck, CEO of Witeck-Combs Communications, Inc., a Washington D.C.--based public relation and marketing communication firm. In the same vein, blogs in the States often serve as opinion forums attempting to stir grassroots movement, or as another journalism tool, he and other media experts say.

"Blogs give the individual the power to publish magazines, newspapers, commentary, and to simply express views and interests without editorial censorship. It's something that seems to be considered the birthright of every American, a fundamental right to self-expression," Witeck explains.

Daniel Dolan, a professor of business communication at Tohoku University, agrees. "News, technology and political blog sites are most popular in the United States, while in Japan the most commonly visited blog sites are diary-style sites. In fact, the very first widely read blogs sites in the United States were political blogs."

Mixi's president claims his site tries to offer a feeling of being more true to life. He and others believe knowing when others are logged on or who visits their profile pages gives a feeling of being linked to other people as well as being monitored by them and may, in turn, lead to more responsible use of the site than others.