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Sanankou: three concealed triplets
Sanankou scores 2 han for three concealed triplets or kans, even with an open group. Ron on a shanpon wait does not count as concealed.
Sanankou rule and value
Sanankou (三暗刻) requires three concealed triplets or kans. The individual groups matter, not the open or closed status of the entire hand. A fourth group called by chi or pon does not prevent sanankou when the other three triplets were formed without an opponent’s discard. The yaku is always worth 2 han.
Ron or tsumo on the third triplet
The winning action often decides the result. Tsumo that completes the third triplet keeps it concealed. Ron on a shanpon wait instead makes the completed triplet open because the winning tile came from another player. If only two concealed triplets existed before that ron, sanankou is lost.
Yaku that combine with sanankou
Ron can still complete sanankou when it fills the pair on a tanki wait: the three triplets already existed and remain concealed. Sanankou often combines with toitoi, yakuhai, or honroutou, but each pattern must be checked independently.
From sanankou to suuankou
Four concealed triplets raise the possibility of suuankou, although its winning conditions are stricter. Do not confuse yakuman potential with sanankou already in hand. In a real game, securing a sound 2-han win is often better than refusing it for a rare upgrade.
Rules references
- Tenhou rulesReference profile used for game mechanics and scoring.
- WRC Rules 2025International rules compared whenever their options differ from Tenhou.