word of mouth

I heard that some men were talking about memorial YAMANOTE line as named 100 years ago.It's "Ad Train" I introduced yesterday.Ad Train can't reach to a lot of people than mass media,but it produces "word of mouth"
Ad market 2010 of "word of mouth by blog" will grow up to 13.2billion yen,
YANO research announced at Feb 2008
http://www.yano.co.jp/market_reports/C49203800