Kokushi musou: Difference between revisions

'''Kokushi musou''' {{kana|国士無双}}, also simply known as '''kokushi''' or in English as '''thirteen orphans''', is one of the standard [[List of yaku#Yakuman|yakuman]] hands. It is one of the three '''yakuman gosanke''' {{kana|役満御三家}}, or "the three big families of yakuman".  This hand is one of the two exceptions of the "[[Mentsu|four tile groups and one pair]]" requirement for [[tenpai]] hands, where the other exception is [[chiitoitsu]]. In fact, hands for this yakuman involve individual tiles while including a [[pair]].

This yakuman is unique, as it requires of one of each [[terminal]] tile from each suit and one of each of the [[jihai|honor tiles]]. The 14th tile must be a duplicate of any terminal or honor tile. These tiles are classed as '''yaochuuhai''' {{kana|幺九牌}}. As the hand requires specific individual tiles, this hand remains closed to qualify, due to the general inability to call tiles in order to complete it. If a player draws the thirteen different tile types before pairing any of them, then the hand is called '''kokushi musou juusan menmachi''' {{kana|国士無双１３面待ち}}, or the [[Machi|kokushi musou 13 closed wait]].

Restricted as closed only, this hand must draw at least 12 of the 13 tile types, among the honors and terminals.  If a pair exists within the hand upon [[tenpai]], then naturally, the hand is waiting on the last remaining tile type not yet in the hand. In turn, this hand will be deemed [[karaten|impossible for completion]], when all 4 of any of the tile types are no longer available.  Yet, if a player manages to develop the 13 wait variety, then this hand greatly increases its chances of completion, needing to simply pair any of the 13 types.

Reasonable development of this hand begins with a dealt set of tiles that gives a player the option to call [[Tochuu_ryuukyoku#Kyuushu_kyuuhai|kyuushu kyuuhai]]. Declining this option puts the hand on the path to form this yakuman.

Any player attempting kokushi musou makes the decision at the [[haipai|beginning]] of the hand. This decision stems on a couple conditions, by which the primary decision rests on the number of unique yaochuhai at the start. The points and the current [[kyoku|hand]] also influences the decision. Sometimes, players need yakuman in order to win or [[Gyakuten|improve point standing]].

On average, a hand ending in [[exhaustive draw]] ends with roughly 16-19 tiles discarded per player, pending any tile calls. Therefore, every player has that many tile draws to work with. For example, if a hand starts with 9 tiles for the yakuman, then it requires 4 [[shanten|tile draws]] searching for specific tiles.  Usually, barring unusual circumstances, those tile draws are nonconsecutive. If anything, a number of tile draws will be required to even attain tenpai. With that said, the decision to form a kokushi musou must be a decisive one at the [[haipai|very beginning of the hand]].

Realistic chances to complete kokushi musou may require a hand to begin with at least 9 yaochuhai.  Even so, at this point, this gives a player the option to defer and abort the hand, rather than trying for kokushi.

This hand is a yakuman hand.  When dealer, the hand [[scoring|scores]] 48,000 points. For non-dealers, the hand scores 32,000. Some rules may apply double yakuman for the 13-wait variety.