Three concealed triplets 三暗刻 · san ankou

Short answer: Sanankou is a 2-han yaku for holding three concealed triplets — triplets completed from your own draws, not by pon — while the rest of the hand may be open.

Three triplets you completed yourself, without pon — the rest of the hand can be open.

Value	2 han, open or closed
How often	uncommon

Mahjong hand: 3 of characters, 3 of characters, 3 of characters — 5 of circles, 5 of circles, 5 of circles — 2 of bamboo, 3 of bamboo, 4 of bamboo — 7 of bamboo, 7 of bamboo, 7 of bamboo — 9 of circles, 9 of circles — Three triplets formed without calling — the fourth set may be anything.

The opportunity usually shows up as pairs. When your draws keep doubling up instead of linking into sequences, and two of those pairs grow into concealed triplets, called ankou 暗刻, you're in sanankou territory. The fourth set is free: you can call pon or chii for it without harm, since only the three triplets themselves have to stay concealed.

The wait decides everything. If the third triplet is still a pair at tenpai and you're on a shanpon シャンポン (two-pair) wait, a ron completes that triplet with a claimed tile, so it counts as open and sanankou is gone. The same tile by self-draw counts. Given the choice, finish all three triplets first and shape the wait around the pair or a sequence, so that ron and tsumo both score.

Stacked with toitoi it reaches 4 han before dora, and concealed triplets carry heavy fu, so these hands pay better than their han count suggests. The reflex to unlearn is calling pon on the third triplet — one call quietly downgrades the hand. And if a fourth concealed triplet is live, you're a step from suuankou.

Key points

The three triplets must be concealed: drawn, not claimed by pon
A triplet completed by ron does NOT count as concealed — a classic scoring trap
One concealed triplet away from suuankou, a yakuman

Worked example

Mahjong hand: 2 of characters, 2 of characters, 2 of characters — 5 of circles, 5 of circles, 5 of circles — 7 of bamboo, 7 of bamboo — 9 of bamboo, 9 of bamboo — 3 of characters, 4 of characters, 5 of characters, winning tile: 7 of bamboo — Tenpai on a two-pair (shanpon) wait: 7s or 9s. Two concealed triplets are already made; the third depends on how the win arrives.

This hand holds two concealed triplets (222m and 555p), a 345m run, and two pairs, 77s and 99s. It waits on either pair turning into a triplet. Draw the 7s yourself and 777s is concealed too: three concealed triplets, sanankou, plus menzen tsumo — 3 han.

Now let an opponent discard the 7s and call ron. The triplet was finished with a claimed tile, so it counts as open, and the hand has only two concealed triplets. No sanankou — and with no riichi, this hand has no yaku left at all, so the ron is not even legal. Same tiles, same wait: the method of winning decides the yaku.

Common mistakes

Counting a triplet finished by ron as concealed. It counts as open (a minkou), for yaku and for fu.
Calling pon on the third pair to "complete" the triplet. The pon makes it open; the other sets can be called, the three triplets cannot.
Missing what it combines with. Sanankou plus toitoi (all triplets) is 4 han. A fourth concealed triplet makes the hand suuankou, a yakuman, which replaces the regular yaku instead of adding to them.

Related yaku

All triplets 対々和 — A hand of four triplets (or kans) and a pair — no sequences at all.
Four concealed triplets 四暗刻 — Four triplets, all formed without calling.
Three kans 三槓子 — Declare three kans in one hand — open, closed, or added, in any mix.

← All yaku · New here? Learn why every hand needs a yaku or check what this hand pays with the score calculator.