Searching in Russian more complex than in Japanese?

The Russian leading search engine Yandex (short for "yet another indexer") controls 56% of the Russian market, compared with Google’s only 23%.

The lead up is apparently given by the complexity of the Russian language, which Google’s engineers have yet to master.

I believe the Japanese language is at least as complex as the Russian language.

Why don’t we have a home-grown leading Japanese search engine in Japan?
The leading search engine in Japan is... Yahoo.