TOKYO — Twitter Inc. now speaks Japanese — and it plans to be multilingual within months.

The popular microblogging service launched a Japan-based mobile version Thursday, hoping to penetrate a country where other U.S. social networking sites including Facebook and MySpace have failed to capture much ground.

Japanese is Twitter's sole foreign language platform so far, and the company's efforts here indicate it's serious about making it big in Japan — and eventually all over the world.

Twitter teamed up with Tokyo-based Internet firm Digital Garage Inc. in early 2008. It launched a Japanese-language platform for cell phones and other mobile devices in the spring of 2008, and hired a Japan manager earlier this year.

"It's an excellent opportunity for us to see where we can go in Asia in general because Japan represents a leading edge, with advanced mobile usage," said Twitter co-founder Biz Stone, who traveled to Tokyo this week for the launching. "Mobile is in Twitter's DNA."

The company will roll out the site in Spanish, German, French and Italian over the next few months, Stone added.

The San Francisco-based company is also using Japan to experiment with ways to make money from features unavailable on its English language site, such as banner ads. It remains mum on how much revenue the ads have attracted so far.

Early adopters were largely male tech geeks, but the messaging service is finally gaining some traction in mainstream Japan. Between January and June, the number of users jumped almost fourfold to 783,000, according to Internet research firm NetRatings.

Japanese celebrities and politicians are starting to sign up.

Yukari Matsuzawa, Twitter's Japan country manager, says that users — and their own ingenuity — will ultimately determine Twitter's fate in Japan.

"As Japanese people creatively start to use Twitter, it will help define what the tipping point will be," she said. "It will be a combination of excellent innovative users in Japan, as well as more celebrities and influential people."