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 2020 Pacific League Climax Series (PLCS) was Nippon Professional Baseball's (NPB) playoff series to decide which Pacific League (PL) team would advance to the 2020 Japan Series. Due to the COVID-19 pandemic, the PL decided to modify the traditional Climax Series format and eliminate the First Stage series to instead only play one modified Final Stage series: a best-of-five series, with the PL champion receiving an automatic one-win advantage over the league's runner-up. The Fukuoka SoftBank Hawks, the league's champion, competed against runner-up Chiba Lotte Marines to determine who would advance to the 2020 Japan Series. The series was played from November 14 to 15 at Fukuoka PayPay Dome. With the advantage and two consecutive come-from-behind wins, the Hawks advanced past the Marines to the Japan Series and the Hawks' Akira Nakamura was named the series' Most Valuable Player. SoftBank will compete against the Central League's (CL) regular-season champion, the Yomiuri Giants, in the Japan Series. Because of the pandemic, the CL cancelled their Climax Series altogether, instead opting to send their regular-season champion.