The Seibu Lions added the prefecture name "Saitama" in front of the team name starting with this season.
As to reduce the interference to teams whose main players would play in the Olympic Games, this year's trade and new foreign players deadlines were pushed to the end of July, instead of the end of June. Also, teams having more than three players selected by National teams were given an extra quota of foreign player limit during the Olympic Games.
The postseason playoff ("Climax Series") regulations have changed to give more advantages to League Champions, now the second stage series will play for 6 games, while the League Champion will have a one-win advantage.
In late June, the Free Agency regulation was amended after negotiation between the players committee and owners. Players are now eligible for free agency after 8 years of service to a team (1 playing year = 145 days on the active roster), players drafted before 2007 are shortened to 7 (University/Company/Independent League) to 8 (High School) years. However, oversea FA right which allow them to play in the Major League Baseball still needs 9 playing years. This amendment is also effective on non-Japanese players. Alex Ramírez, who served 8 playing years in Japan, became a "local player" after the season.
Note: Whenever multiple teams have same number of wins, the team having better standings in last year's interleague games will have advantage, thus Fukuoka SoftBank Hawks won the interleague title, despite Hanshin Tigers beating the Hawks 3 out of 4 games. A similar rule applies to other teams tied in wins.
^In NPB, no team can have more than 4 "non-local" players in their active roster, and they cannot be all pitchers or all fielders, non-Japanese players who entered NPB by draft, or obtained the FA right are not bounded with this restriction.