in baseball, a seven-game playoff between champions of the two professional Japanese baseball leagues, the Central League and the Pacific League. Baseball in Japan was established on a professional basis in 1934, and by 1936 seven professional teams had been organized. A system of two leagues composed of six teams each was instituted in 1950. Each 135-game season culminates in the Japan Series. The Yomiuri (Tokyo) Giants have been the dominant team in the Japan Series, with a total of 19 championships for the years 1950–2000. The next closest team, the Seibu Lions, won 11 championships over the same period.