Overview
Extra innings are additional frames played when the score is tied after nine innings. In NPB's first-team official games extra innings stop after the 12th, and a game still tied at that point is recorded as a draw. Neither the 12-inning cutoff nor the draw comes from the Official Baseball Rules themselves: the rules leave that point to the governing body, and NPB settled it this way (see below). Draws almost never survive in MLB records, and because they count as neither a win nor a loss they also shape the pennant race standings. Extra innings are normally worked by relievers, so which arms a manager still has available often decides the game. As special measures during the COVID-19 years, NPB capped extra innings at the 10th in 2020 and played with no extra innings at all (nine-inning cutoffs) in 2021, before returning to the usual 12-inning format in 2022. How the tiebreaker (placing a runner on second base to start each extra inning) sits in the rulebook is covered below; as of August 2026 NPB's first-team official games still run on the traditional 12-inning format.
Where the 12-inning cap comes from
The Official Baseball Rules say nothing about how many extra innings may be played. Rule 7.01(b) provides only that when both clubs have completed nine innings with the score tied, play continues inning by inning until either the visiting club leads at the end of a full extra inning or the home club scores the winning run in the bottom half; no maximum is given. Paragraph (d) then treats a regulation game that ends with the score tied as a suspended game to be resumed later, and the Japanese edition attaches a note saying that in Japan the rules of the governing body apply. In other words, how a tie is settled is left to the governing body rather than to the rulebook, and the 12-inning cutoff with a draw is the arrangement NPB made for its first-team official games. Draws almost never appear in MLB records because MLB follows the rulebook and resumes tied games on a later date. Nor is NPB the only league that keeps draws: the KBO League in South Korea also caps extra innings and allows draws, and from 2025 it shortened that cap from 12 innings to 11 in view of the load the newly introduced pitch clock places on pitchers.
Tiebreakers and the rules for extra innings
The tiebreaker was introduced provisionally by MLB in 2020 and made permanent in 2023, and the 2024 revision wrote it into the Japanese edition of the Official Baseball Rules as well. The heading of Rule 7.01(b) became Extra Innings, and a new paragraph (2) provides that once nine innings are complete, play from the tenth on begins with a runner on second base. The leadoff hitter of an extra inning continues the batting order from the previous inning, and the runner placed on second is the player who precedes that leadoff hitter in the order (if that spot belongs to the pitcher, the player before him may take the base instead). For the purpose of earned runs the runner is treated as having reached second on a fielding error, but no error is charged to any club or player, and the plate umpire checks the offense's batting order at the start of each extra inning to confirm the runner is the correct one. Paragraph (2) also carries the note that in Japan the rules of the governing body apply, so adoption is left to each organization. NPB's first-team official games have not adopted it, and as of August 2026 the 12-inning cutoff and the draw remain in place. The 2025 revision addressed the use of pitchers in extra innings: a club may make four trips to the mound without changing pitchers over nine innings, and once extra innings begin it may make one such trip per inning.