How many professional baseball teams are there in Japan?

There are 12 teams in totalix in, six the Central League and six in the Pacific League.
The 12 teams have farm teams, which comprise the Eastern Leacue and the Western League.
Baseball was introduced to Japan in 1877, and the DaiNihon Tokvo Yakvu Club, the forerunner of the present Yomiuri Gianls, was founded in 1934.
The Japan Professional Baseball League was launched in 1936 with seven teaｍs, and the two-league system was introduced in 1949.
In 1995, Japanese pitcher Nomo Hideo made his debut in the Major League in the United States and had a successful first year, which created awareness about Japanese professional baseball.
Following Nomo, several other Japanese players (Ichiro, Matsui Hideki, etc.) have also become active in the American major leagues.