Pair

A pair (jantou or atama, 'the head,' in Japanese) is two identical tiles, such as 9m-9m or two Red dragons. In the standard winning structure of four melds plus a pair, exactly one pair is required and it is the only two-tile group in the hand. The pair can be made from any tile type, including number tiles, winds, and dragons, though the choice of pair tile can carry scoring consequences.

The pair plays a quieter role than melds but is strategically important when you are deciding your wait. A 'pair wait' or tanki wait occurs when your hand is complete except for a single tile that will become the pair, for example holding a lone 5p that you hope to match. This is one of the narrower waits, with at most three tiles remaining, and it appears often in late-game hands and in special structures like the thirteen orphans.

Variant rules attach value to certain pairs. In Japanese riichi the pair must be a non-value tile (not a dragon, not your seat or round wind) for the pinfu yaku to apply, and a pair of dragons or your own wind adds fu. Some hands break the four-melds-plus-pair mold entirely: seven pairs (chiitoitsu) is made of seven distinct pairs and has no melds at all, while thirteen orphans uses one pair among its terminals and honors.

For example, a hand reading 234m 567p 678s 11z waiting on a fourth East-wind-adjacent tile may instead settle its pair as 1z-1z (East). If East is your seat wind, that value pair adds fu but disqualifies pinfu, illustrating how the humble pair shapes both completion and scoring.