Pair wait

A pair wait, also called a tanki wait in Japanese Riichi, occurs when every set in your hand is already complete and the only missing piece is the second copy of your pair tile. Your hand sits on a single lone tile, and you win by drawing or claiming the matching tile to form the pair. Because there are four of each tile in the wall, a pair wait accepts at most three remaining copies, fewer if you can see others discarded or melded.

For example, if you hold three complete runs and triplets plus a lone East wind, you are waiting on the second East to finish. Any tile can anchor a pair wait, which gives it surprising flexibility: you can switch which tile you sit on more freely than with a run-based wait, making it useful for dodging furiten or fishing for a higher-value winning tile.

In Riichi scoring the pair wait grants 2 fu, the same bonus given to edge and closed waits, because it is considered a harder single-tile wait. It is also the only wait that lets the pair itself be a value tile, so winning on a yakuhai pair (a dragon or seat/round wind) by tanki can add fu and sometimes interacts with hand structure.

Pair waits matter in advanced strategy because they enable certain yaku and limit hands. The chiitoitsu (seven pairs) hand is always finished on a pair wait by definition, and the kokushi musou (thirteen orphans) hand has a powerful thirteen-sided pair-wait form. Across Chinese, Hong Kong, and Taiwanese variants the shape behaves the same structurally, though only Riichi attaches the fixed fu bonus and the furiten rule that can lock you out of winning on your own discarded pair tile.