Yaku guides · 6 / 17
Kokushi musou: thirteen orphans
Kokushi musou is a closed yakuman made from all thirteen distinct terminals and honors, plus one duplicate among them.
The principle
Kokushi musou (国士無双) uses the 1 and 9 of all three suits, the four winds, and the three dragons. The hand needs all thirteen distinct types and a duplicate of any one of them for its fourteenth tile. This special structure uses no ordinary sequences or triplets and is worth one yakuman.
Rule and example
When all thirteen types are present once, the hand waits on any of them: the thirteen-sided wait. When one type is already paired and another is missing, only the missing type completes the hand. Tenhou and WRC 2025 score both forms as a single yakuman.
What changes
The hand must remain closed, and chi or pon cannot contribute to its structure anyway. Furiten applies normally. On the thirteen-sided wait, having discarded even one of the thirteen winning tile types prevents every ron while that wait remains unchanged.
Mistake to avoid
A starting hand rich in terminals and honors can justify a kokushi route, especially when the standard hand is far away. Every middle tile drawn still reveals the cost of that plan. Compare special and standard shanten before giving up too much speed.
Rules references
- Tenhou rulesReference profile used for game mechanics and scoring.
- WRC Rules 2025International rules compared whenever their options differ from Tenhou.