Overview
Interleague play in NPB pits Central League teams against Pacific League teams in official regular-season games, introduced in 2005. The immediate catalyst was the 2004 restructuring crisis involving the Kintetsu-Orix merger and single-league proposals, prompting measures to revitalize fan interest. Initially comprising 36 games per team (six per matchup), the format has been reduced to 18 games (three per matchup). Interleague play also serves as a barometer of league strength: the Pacific League has maintained an overall winning record since inception, attributed to roster construction differences under the DH rule and aggressive Pacific League acquisition strategies. Matchups between teams that rarely face each other provide novelty for fans, and regional scheduling helps cultivate new audiences.