Kokushi musou

Kokushi musou

Type	Yakuman
Kanji	国士無双 国士無双１３面待ち
English	Thirteen orphans
Value	Yakuman (closed only)
Speed	Slow
Difficulty	Hard

Kokushi musou 「国士無双」, also simply known as kokushi or in English as thirteen orphans, is one of the standard yakuman hands. It is one of the three yakuman gosanke 「役満御三家」, or "the three big families of yakuman". This hand is one of the two exceptions of the "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.

Composition

This yakuman is unique, as it requires of one of each terminal tile from each suit and one of each of the honor tiles. The 14th tile must be a duplicate of any terminal or honor tile. These tiles are classed as yaochuuhai 「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 「国士無双１３面待ち」, or the kokushi musou 13 closed wait.

Tile diagram

The hand requires nothing but yaochuuhai.

Kokushi musou single wait

Winning tile:

Kokushi musou 13-way wait

Winning tile: Any one of the tiles shown here

• Winning from this wait may be worth two yakuman in some rules.

Meaning and usage

The word kokushi can be translated as "distinguished citizen"; the word musou is often translated as "peerless". The word kokushi should not split up and expressed as "Koku shimusou". This is an incorrect spelling.

Development

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 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 kyuushu kyuuhai. Declining this option puts the hand on the path to form this yakuman.

Attempting kokushi

Kokushi musou with real tiles.

Sample successful attempts

Hand	Yaochuhai start	Discard at tenpai	Result	Lobby	Link
東 2 局 1 本場	9	9th	Ron after 12th	上級	[1]
東 2 局 1 本場	9	6th	Ron after 6th	7447	[2]
南 3 局 0 本場	10	4th	Ron after 5th	鳳凰	[3]
南 1 局 2 本場	8	15th	Haitei ron	特上	[4]
南 4 局 0 本場	7	11th	Ron after 12th	上級	[5]
南 2 局 0 本場	11	2nd	Ron after 2nd	7447	[6]
東 2 局 1 本場	9	6th	Tsumo on 8th	鳳凰	[7]
Yaochuhai start includes the initial draw.

Any player attempting kokushi musou makes the decision at the 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 hand also influences the decision. Sometimes, players need yakuman in order to win or 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 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 very beginning of the hand.

13-way wait development

Kokushi musou juusan menmachi is very rare. Out of all random tile draws that result in tenpai for kokushi, the chance of naturally drawing all 13 tiles without a single duplicate is approximately one in 9500 (~0.0106%). The only "consistent" way to achieve the double yakuman is to complete kokushi via tsumo, but discard the pair and hope to complete the hand while in furiten.

Kyuushu kyuuhai

Main article: Tochuu ryuukyoku

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.

Value

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

Chankan rule variation

Case where a closed kan was declared during a kokushi tenpai.

Under some rules, a kokushi tenpai hand may win via chankan off a closed kan made with the winning tile. When allowed, this is an exception to the usual rule that ron may be called off of the tile used to form an added kan, but not a closed kan. This rule, although not universal, is fairly common.

External links

• 国士無双

Kokushi musou in Japanese Wikipedia

• Kokushi advice

Osamuko.com entry on Kokushi

• 【麻雀】沢崎誠の国士無双13面張！！ (YouTube)

Kokushi 13, while furiten