Overview
The pennant race refers to the regular-season competition for the league championship in NPB. Six teams in each of the Central and Pacific Leagues play 143 games per season (including interleague play), with final standings determined by winning percentage. The 'pennant' is the championship flag awarded to the league winner. The pennant race is inseparable from NPB history itself, having been contested annually since the two-league system began in 1950. The number of games has evolved over the decades, moving through a 130-game era before settling at the current 143. The introduction of interleague play following the 2004 restructuring crisis added a new variable, and the Climax Series playoff system adopted in 2007 meant that the pennant winner no longer automatically advanced to the Japan Series. Critics argue this diminished the pennant race's significance, while supporters point to the commercial benefit of keeping more teams in postseason contention deep into the season. Tracking magic numbers, games-behind fluctuations, and head-to-head results as the pennant race unfolds is one of the core pleasures of following NPB.