Nippon Professional Baseball playoffs

The Nippon Professional Baseball (NPB) playoffs have taken several different forms throughout the organization's history. Japanese baseball is divided into two leagues; the Pacific League (PL) is less popular and less profitable than the Central League (CL). As a result, the PL has employed various playoff formats throughout its history in an effort to increase fan interest. The PL's first true playoff system was introduced in the 1973 season. It involved a split season plan that divided the season into two halves and the two teams that won each half went on to play each other in a five-game playoff series, with the winner advancing to the Japan Series. While popular with fans, the format was scrapped after ten seasons because of major issues and criticisms. In the year following their last split season, the PL returned to a single season, however if five or fewer games separated the first- and second-place teams at the end of the season, the two teams would play each other in a five-game playoff series. This playoff system was unpopular and ridiculed by media and fans. It only lasted three seasons with a playoff series never needing to be played.

With their first two playoff systems abolished, the Pacific League returned to simply advancing their regular-season champion directly to the Japan Series. During this time, the PL's Seibu Lions won six Japan Series championship titles in seven seasons from the mid-1980s to the early-1990s. After the fall of the Lions in the mid-1990s, the league struggled to win championships against the Central League and lost three consecutive Japan Series to start the 2000s. Again fighting for its survival as its popularity faded, the PL board of directors agreed to reintroduce a playoff system to be used in the 2004 season to potentially create more regular-season excitement. The new postseason plan initiated a two-stage playoff in which the top three PL teams competed. In the First Stage, the teams that finished the season with the second- and third-best records played each other in a best-of-three series. The winner of this series faced the league's top finisher in the second, best-of-five stage. The winner of the Second Stage advanced to the Japan Series, where they competed against the CL's regular-season champion. After two years, the rules were changed to award the first-place team an automatic one-win advantage in the Second Stage. Though Central League officials initially criticized the plan, the PL's playoffs were a success and soon after the CL was criticized for not implementing a playoff system of their own.

Unlike the Pacific League, the Central League had never experimented with any type of postseason system prior to 2006. They had situational playoff scenarios written into its bylaws in the event of an end-of-season tie, however, it never occurred and a permanent playoff plan had never been created. In 2006, encouraged by the success of the PL's postseason system, CL officials announced their intention to introduce playoffs for the 2007 season to help boost declining attendance. Later that year, PL and CL officials agreed on a unified postseason system. The CL implemented a playoff system identical to the PL's, and the entire playoff series was dubbed the Climax Series, NPB's current playoff format. The PL agreed to name the regular-season first-place finishers league champions rather than the team that won the leagues' respective playoffs—a reversal from the previous three seasons. The two leagues also agreed that neither regular-season champion should receive a one-game advantage in the Final Stage of the Climax Series. However, after one season, the leagues overturned their decision on the Final Stage advantage and agreed to award their champions a one-win advantage in the Final Stage starting with the 2008 Climax Series. At the same time, the Final Stage changed from a best-of-five series and became a best-of-seven series, where the first team to accumulate four wins advances to the Japan Series.