Giant of Search and Portal in Japan

Compared to Yahoo! US, Yahoo! Japan is very strong. Yahoo! Japan's share of searches is 52% in Japan , while Yahoo!'s share of searches is 20% in US.

Source：Nielsen Online NetView(Japanese)

Source: comScore Releases April 2009 U.S. Search Engine Rankings
In terms of reach, Yahoo! Japan is dominant in Japan. Yahoo! Japan has 83.5% of reach in Japan, while Yahoo! in US has 61.9% of reach there.
Yahoo! Japan

Yahoo!

Source: Google Ad Planner