The 2020 Japan Series was the championship series of Nippon Professional Baseball's (NPB) 2020 season. The 71st edition of the Japan Series, it was played from November 21 to 25. The series was a best-of-seven playoff between the Fukuoka SoftBank Hawks, the Pacific League's (PL) Climax Series champion, and the defending Japan Series champions, and the Yomiuri Giants, the Central League's (CL) regular-season champion. The series was a rematch of the previous year's Japan Series.

The Saitama Seibu Lions are a professional baseball team in Japan's Pacific League based north of Tokyo in Tokorozawa, Saitama Prefecture. Before 1979, they were based in Fukuoka, Fukuoka Prefecture in Kyushu. The team is owned by a subsidiary of Seibu Railway, which in turn is owned by the Seibu Holdings. The team experienced a recent period of financial difficulty, but the situation brightened when the team received a record ¥6 billion posting fee from the Boston Red Sox for the right to negotiate a contract with Daisuke Matsuzaka. Between 1978 and 2008, the team logo and mascot were based on the adult version of Kimba the White Lion, a classic Japanese anime and manga series by Osamu Tezuka. In 2004, former Seibu Lions player Kazuo Matsui became the first Japanese infielder to play in Major League Baseball.