How big is the Japanese search market exactly? Japan is the 3rd biggest country by the number of Internet users. See other statistics from Japanese government and research organizations.
The summery of online advertising market in Japan in 2008. Review the market from display ads, text ads, ad portals, etc. Also information about "Internet advertising Value Index Project" by major online businesses in Japan such as Yahoo and Microsoft.
Mobile Internet and mobile search have a long history in Japan. These are some of th e points, which you should know about mobile internet, mobile web and mobile search in Japan that would lead you to successful mobile SEO and SEM campaigns.
Mobile advertising grew to 81.5 billion yen market in 2007, and expected to hit 100 billion yen in 2008 in Japan. This will definitely push mobile paid market to grow rapidly in Japan within a few years.
The advertising market in Japan grew to more than 3 billion yen market in 2007 from 0.9 billion yen market in 2006. Their another survey shows that more than 80% of net users have actively taken the advise/information they got through "word-of-mouth" on the net.
On Feb 15, I spoke about Japanese Internet Market during the Search Around The World session at Search Engine Strategies Paris. It was the only session provided in English. I was happy to see we had a good attendance to the session.