Yakuhai

Yakuhai is the umbrella term in Japanese Riichi for the value tiles that score a yaku simply by being collected into a triplet (pung) or kong. The qualifying tiles are the three dragons (white, green, red) and the two situational wind tiles: your seat wind and the current round wind. A completed set of any of these is worth 1 han, and because the yaku requires only a triplet, it is one of the easiest ways to open a hand and still have a valid winning condition.

Each dragon counts independently, so a hand holding triplets of two different dragons scores 2 han, and a third would make Shousangen (little three dragons) territory. Winds are trickier because of double counting: in an East round, the East player's East-wind triplet is both seat wind and round wind, scoring 2 han at once — sometimes nicknamed a 'double East.' The other dragons and the non-matching wind triplets give nothing as yakuhai.

The key strategic point is that yakuhai can be claimed open: you may pon a discarded dragon or your wind and still have a legal hand, unlike yaku such as pinfu or riichi that demand a closed hand. This makes yakuhai the backbone of fast, aggressive open hands. For example, holding 5z5z (white dragon) and pon-ing a third 5z instantly secures the yaku, freeing you to chase the remaining sets in any suit. Beginners often misremember that a guest wind — say a West tile when you sit East in an East round — scores; it does not. Only the seat and round winds, plus all three dragons, are yakuhai.