San'ankou (三暗刻)
Three concealed triplets.
How San'ankou (三暗刻) works
Three concealed triplets within the hand, each formed without calling — the fourth set and pair may be anything.
San'ankou requires three triplets that were completed in hand rather than by pon, with the remaining set free to be a chow, a melded triplet, or another concealed triplet. A subtle rule: a triplet completed by ron counts as open, so the winning tile generally must be drawn or land in a non-triplet position for all three to qualify. It frequently overlaps with toitoi and, when a fourth concealed triplet is present, points toward the suuankou bonus.
- •The triplets must be concealed; a ponned triplet does not count toward the three.
- •A triplet completed by ron is treated as open, which can cost you the third concealed set.
- •It can coexist with open melds elsewhere in the hand, since only three sets need to be concealed triplets.
San'ankou (三暗刻) — FAQ
Does a triplet finished by ron count as concealed?
No. A triplet whose final tile comes from a discard is considered open for this purpose, so winning by tsumo is often needed to secure all three.
Can my hand be open and still score sanankou?
Yes. Only three sets must be concealed triplets; the remaining set may be a called meld.