Professional baseball in Japan first started in the 1920s, but it was not until the Greater Japan Tokyo Baseball Club (大日本東京野球倶楽部 Dai-nippon Tōkyō Yakyū Kurabu?) was established in 1934 that the modern professional game had continued success.
Baseball was introduced to Japan in 1872 by Horace Wilson, and its first formal team was established in 1878. For almost 30 years, until 1906, a game could be viewed free of charge, as it was considered shameful to take money for doing something the players liked.
In 1907, the first game was held that had a fee to watch. From 1908, several United States professional teams toured Japan and played against amateur teams made up mostly of university students, including both the Chicago White Sox and the New York Giants in 1913. Realizing that a professional league was necessary to improve, two professional teams were established in 1920. In the same year, teams held exhibition tours in Korea and Manchuria to spread baseball. This first professional league disintegrated in 1923 for financial reasons, and after repeated attempts to revive a professional league, it formally disbanded in 1929.
The American Major League Baseball outfielder Lefty O'Doul was instrumental in spreading baseball's popularity in Japan, serving as the sport's goodwill ambassador before and after World War II.
In 1934, Greater Japan Tokyo Baseball Club (大日本東京野球倶楽部 Dai-nippon Tōkyō Yakyū Kurabu?) was established, reviving professional baseball. A second team, Osaka Baseball Club (大阪野球倶楽部 Ōsaka Yakyū Club?) was established in the following year. The former became the Yomiuri Giants (O'Doul dubbed the team the "Tokyo Giants") and the latter became the Hanshin Tigers. In 1936, five other teams also formed, and the Japanese Baseball League was started. Briefly forced to stop playing for a year beginning in 1944, it restarted on November 6, 1945, and a full season was played the next year.