Sanankou Yaku: Three Closed Triplets

Sanankou ("three concealed triplets") forms when you have THREE closed (concealed) triplets -- meaning formed by drawing your own tile (tsumo) or already in hand from the start, NOT from a Pon.

Key Detail: A Ron-Completed Triplet Still Counts as Closed

There's a commonly confusing exception: if your third (or later) triplet is completed via a Ron (winning off an opponent's discard), that triplet STILL counts as closed for Sanankou purposes -- unlike a Pon, which obviously makes that triplet open.

Value and Combos

Sanankou is worth 2 han, and can combine with Toitoi (if all four sets are triplets, three of them closed) for a fairly expensive hand, especially with Yakuhai added.

An example Sanankou hand -- three closed triplets (111m, 222p, 333s), plus one sequence and a pair.