Overview
The Climax Series (CS), introduced in 2007, is a postseason system where the top three teams in each league compete for the Japan Series berth. It consists of the First Stage (2nd vs 3rd place, best-of-3) and Final Stage (1st place vs First Stage winner), with the pennant winner receiving a head start in wins. Under a change NPB announced in March 2026, from that season the advantage grows to two wins and the Final Stage expands to a best-of-7 (first to five wins) whenever the First Stage winner finished below .500 or trailed the pennant winner by 10 or more games; if neither condition applies, the Final Stage remains a best-of-6 with a one-win advantage, and the advantage is capped at two wins even when both apply. The First Stage format is unchanged. Its predecessor was the Pacific League playoff system launched in 2004, which sparked controversy in its inaugural year when Daiei, holder of the best regular-season winning percentage, fell to second-place Seibu and handed over the pennant itself. Upsets have continued under the CS format-most notably in 2010, when the Pacific League's third-place Lotte Marines swept through the CS and won the Japan Series in what was dubbed 'the greatest upset in history.' While the CS has reduced meaningless late-season games and heightened pennant race excitement, persistent criticism remains over the perceived injustice of a team winning 143 regular-season games only to be eliminated in a short series. In 2020 the Central League called off its CS amid the pandemic and sent its pennant winner, the Yomiuri Giants, straight to the Japan Series, while the Pacific League still staged a four-game series between its top two clubs, with a one-win advantage for the leader.