Nippon Professional Baseball

Nippon Professional Baseball (日本野球機構, Nippon Yakyū Kikō; NPB) is a professional baseball league and the highest level of baseball in Japan. Locally, it is often called Puro Yakyū (プロ野球), meaning simply Professional Baseball; outside of Japan, NPB is often referred to as "Japanese baseball".

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 1934. The first professional circuit for the sport in Japan, the Japanese Baseball League (JBL), was founded two years later and continued to play even through the final years of World War II. The organization that is today's NPB was formed when the JBL reorganized in 1950, dividing its 15 teams into two leagues, which would meet in the annual season-ending Japan Series championship play-off series of games starting that year.

NPB comprises twelve teams divided equally in two leagues, the Central League and the Pacific League, a format which it has largely kept since 1957. It has seen several waves of expansion and contraction, sometimes at the same time, to keep it at those numbers; most recently, in 2005, the Osaka Kintetsu Buffaloes merged with the Orix BlueWave to form the Orix Buffaloes, while the Rakuten Golden Eagles were added as an expansion team. As is common in Asian baseball (and unlike North American leagues), teams are generally named after their corporate owners, such as Yomiuri and Softbank. NPB also oversees two affiliated minor leagues, the Western League and the Eastern League.

Since the first Japan Series in 1950, the Yomiuri Giants have the most championships with 22, and the most appearances with 37. Following the 2024 season, the Yokohama DeNA BayStars, who defeated the Fukuoka SoftBank Hawks 4–2 in the 2024 Japan Series, are the reigning champions. The Japan Series has been contested 75 times as of 2024, with the Central League leading the Pacific League in wins, 38-37.

NPB was the only professional sports league in Japan until the foundation of the J.League in 1993. It is the eleventh-wealthiest professional sport league by revenue in the world, and the second-wealthiest baseball league, behind Major League Baseball (MLB); it is also the wealthiest sports league in Asia. NPB has the second-highest total season attendance of any league, also behind MLB, despite playing considerably fewer games per season.

Nippon Professional Baseball consists of two leagues, the Central League and the Pacific League, which each have six teams. There are also two secondary-level professional minor leagues, the Eastern League and the Western League, that play shorter schedules for developing players in the so called "Farm System". NPB teams are allowed to have more than one minor league team as long those others are outside of the established farm/minor league system, with the Fukuoka SoftBank Hawks and Yomiuri Giants being the only teams taking advantage of this. As of 2023, the Hawks have three minor league teams, the Giants have two, and the other ten teams only have one minor league team each. Teams below the Eastern and Western Leagues play exhibition matches against various teams of collegiate, industrial, Shikoku Island League Plus, and other NPB minor league statuses.

The Central League and Pacific League operate as separate entities, unlike the four major professional sports leagues of North America and the Korea Baseball Organization, whose leagues each operate as one singular entity. due this factor, the TV rights for games are always held by a game's home team, execpt for Japan Series and All-Star Games, which the league owns the rights in a special colaborative system among the 12 teams in order to avoid blackout issues. The Pacific League has used the designated hitter (DH) rule since 1975, while the Central League plans to introduce DH from 2027 season, before it, the Central League has not used the DH outside of interleague play where a Pacific League team is the home team and in the 1985 Japan Series.

The season starts in late March or early April, and ends in October, with two or three all-star games in July. In recent decades prior to 2007, the two leagues each scheduled between 130 and 140 regular season games, with the 146 games played by the Central League in 2005 and 2006 being the only exception. Both leagues have since adopted 143-game seasons, 71 or 72 each at home and on road, facing their five respective intra-league opponents 25 times each and facing their six interleague opponents three times each in late May to early June in interleague play, with a separate champion being crowned for the team with the best record through the 18 games of interleague play. In general, Japanese teams play six games a week, with every Monday off (except on specific occasions, such as a game being played outside of the home team's primary stadium or if a rainout forced a game to be postponed to a Monday). Unlike in Major League Baseball and in KBO League, doubleheaders have not been featured in NPB since the late 1990s.