Riichi Mahjong Yaku
Four Concealed Triplets
Also known as: Suuankou · Suanko · 四暗刻
Four concealed triplets or quads and a pair, completed without opening the hand.
Yaku value
Closed hand
Yakuman
Open hand
Closed only
Requirements
Build all four groups as concealed triplets or concealed quads. A Tsumo win always preserves all four concealed groups.
Common scoring mistake
With a two-sided pair wait, winning by Ron completes a triplet from another player’s tile and usually does not qualify. A single-pair wait can qualify by Ron.
Values follow common modern Riichi rules. Local and tournament rules may differ, especially for double Yakuman.