Why is Yahoo bigger than Google in Japan?

Found this post on mashable.com about Yahoo being bigger than Google in Japan - when it comes to search. Why?

Stan Schroeder attributes this to things being different in Japan; for example the iPhone is struggling for market share there. Japan is way ahead of the rest in the world in technology, and it looks like that the iPhone is well behind in features compared to local phones. Japanese phones are built in with QR readers, fingerprint readers, watch TV, higher resolution cameras, conference call features and IC chips to charge for purchases, ex. transit tickets!

So why is Yahoo! bigger than Google there? I look at the Yahoo! and Google sites, and Google's simplistic approach is definitely more effective in my opinion. You visit google.com and you know what Google does - Search. On the other hand a visit to yahoo.com is overwhelming. This is true in the case of the Japanese version of both sites as well:
http://www.yahoo.co.jp/
http://www.google.co.jp/

So yes, things are different in Japan, but I am curious to know what is different that makes Yahoo! more popular than Google. Is this tied somehow to the local super-phones? and perhaps that is why on the Japanese Google site there are links to mail, youtube, news and maps at the top and under the search unlike the .com site where they are only present at the top.