Recap
The roots of the league can be traced back to the formation of the "Greater Japan Tokyo Baseball Club" (大日本東京野球倶楽部 Dai-Nippon Tōkyō Yakyū Kurabu) in Tokyo, founded 1934 and the original circuit for the sport in the Empire two years later - Japanese Baseball League (1936-1949), and surprisingly even continued to play through the dark years of total warfare with Japan's invasion of Manchuria (northeast China) in 1931, and intervening in the Chinese Civil War in 1937 with the wider Sino-Japanese War (1937-1945), and into the greater World War II (1939-1945).
The league was established on February 5, 1936, as the Japan Occupational Baseball League, with an initial complement of seven teams. Three of the teams were based in Tokyo, two in Osaka, and two in Nagoya. The league played fall and spring seasons in 1937 (c. 100-game schedule, in total) and 1938 (total 75-game schedule), adding one new team each year. It was renamed the Japanese Baseball League in 1939, playing a 96-game schedule. Before the 1940 season, one of the founding teams, Nagoya Kinko (originally the Nagoya Golden Dolphins), merged with the Tokyo Senators. The 1940 season featured a 104-game schedule.
In October 1940 (responding to rising hostility toward the West due to World War II), the league outlawed the use of English in Japanese baseball. In response, the Korakuen Eagles became "Kurowashi", the Osaka Tigers became "Hanshin", the Tokyo Senators became "Tsubasa", and (eventually) Lion became "Asahi."
In 1941, the JBL appointed its first president, Jiro Morioka (formerly VP of Dai Tokyo). Morioka negotiated with the Japanese Imperial Army to keep professional baseball going through the early years of the Second World War.
The new NPB for Japan was formed when that sports organization reorganized in 1950 with creating its two leagues with six teams each of the Central League and the Pacific League with an annual season ending Japan Series championship play-off series of games starting that year.
I sincerely appreciate the research work, and the information being shared. It is important and interesting history.