Yaku guides · 17 / 17
Iipeikou: two identical sequences in one suit
Iipeikou is 1 han for two identical sequences in the same suit. It needs a closed hand, and two of them score ryanpeikou instead.
The principle
Iipeikou (一盃口) consists of two sequences with exactly the same numbers in the same suit. Two 234m sequences qualify; 234m and 234p do not. The hand must remain closed, and the yaku is worth 1 han.
Rule and example
In 223344m 456p 789s 55z, the first six tiles can be read as two 234m sequences. The matching tiles do not need to have been drawn in any particular order. The final decomposition of the winning hand is what determines the yaku.
What changes
Winning by ron does not open a closed hand, so iipeikou remains valid on ron. It can combine with riichi, menzen tsumo, pinfu, tanyao, chanta, junchan, honitsu, or chinitsu when the other tiles fit. A chi called earlier does remove iipeikou.
Mistake to avoid
Two separate pairs of identical sequences produce ryanpeikou, which is worth 3 han and replaces iipeikou instead of stacking with it. Do not protect a fragile duplicate at any cost: compare shanten and ukeire before refusing a broader shape.
Rules references
- Tenhou rulesReference profile used for game mechanics and scoring.
- WRC Rules 2025International rules compared whenever their options differ from Tenhou.