Curriculum · 14 / 50
The yaku: recap
Yaku chapter recap: the mandatory pattern you need to win, its value in han, closed versus open hands, and the trap of tenpai with no yaku.
The principle
A yaku is a pattern that gives a hand value. The core rule of riichi is simple: you need at least one yaku to declare a win, whether by ron or by tsumo. Dora, aka dora and uradora add han but are not yaku, so they can never win a hand on their own.
Rule and example
Closing the hand changes everything. Some yaku exist only with a closed hand: riichi, menzen tsumo, pinfu, iipeikou and chiitoitsu all become impossible after any call (chi or pon). Others survive when open but lose one han, the kuisagari: sanshoku, ittsu, chanta, junchan, honitsu and chinitsu.
What changes
The chapter reviews common yaku. At 1 han: yakuhai, tanyao, pinfu, riichi and closed-hand tsumo. Heavier yaku include honitsu, chinitsu and toitoi. In an ordinary hand, yaku han add together, then dora are added before fu and payment are calculated.
Mistake to avoid
At the top are genuine yakuman such as kokushi musou, suuankou and daisangen. Under Tenhou, different yakuman stack and an ordinary hand with 13 or more han becomes kazoe yakuman. WRC 2025 calls that ordinary tier yonbaiman. The classic trap remains yakuless tenpai, which cannot win but may count at an exhaustive draw.
Rules references
- Tenhou rulesReference profile used for game mechanics and scoring.
- WRC Rules 2025International rules compared whenever their options differ from Tenhou.