Facebook founder Mark Zuckerberg isn’t visiting China and Japan just for sightseeing and meeting government officials, he’s also down there for surprise appearances at hacker events and gettings things done.

Dentsu, the Japanese marketing and communications giant that ranks up there as one of the largest advertising agencies in the world, this morning announced the continuation of an agreement that it struck with Facebook back in February 2011.

In a press statement (PDF), Dentsu says it will continue to serve as the official representative of Facebook’s sales and marketing support to advertisers in Japan.

(It’s worth noting that Dentsu also has a special relationship with Apple; in fact it is responsible for the ‘selling and creative execution’ of iAds in Japan.)

Dentsu says it will “provide consultation on and support for effective Facebook Page development”, and also guide advertisers with setting up marketing campaigns that leverage the Facebook Premium Ad platform.

The Japanese advertising juggernaut – which has over 20,000 employees worldwide – has the exclusive marketing rights to the latter in Japan.

The previous deal was inked for a duration of one year, but it’s unclear whether that also applies to the renewed agreement.

From the press release:

Based on the expertise gained through working together with Facebook in 2011, Dentsu will continue to encourage the adoption of Facebook Pages to marketers and media companies.

With regard to Facebook Premium Ads, Dentsu will collaborate with both Facebook and cyber communications inc., a Dentsu subsidiary in Japan, to enable more advertising agencies in Japan to market the new Premium Ad formats.

Facebook has recently overtaken local service Mixi as the dominant social network in Japan with 10 million active users and counting. That is roughly 10 percent of the country’s population today.