Kokushi Musou (国士無双)
Thirteen orphans — one of each terminal and honor, plus a pair.
How Kokushi Musou (国士無双) works
Thirteen orphans — one each of all nine terminals and seven honors, with one of those tiles duplicated to form the pair.
Kokushi Musou is a special hand outside the normal four-sets-and-a-pair structure: it gathers a 1 and 9 of each suit plus every wind and dragon, then pairs one of them. It must be entirely concealed, as it cannot involve melds. A thirteen-tile single wait on any of the orphan tiles is one of mahjong's signature shapes and, in many rulesets, allows robbing a kan.
- •Closed hand only; the special shape cannot include any called set.
- •It does not combine with standard yaku since it uses an entirely different hand structure.
- •Holding all thirteen unique orphans gives a thirteen-sided wait, often scored as a higher double-yakuman variant.
Kokushi Musou (国士無双) — FAQ
What is the thirteen-wait version?
If you already hold one of each orphan tile and wait on any of the thirteen to form the pair, many rules award an enhanced version worth more.
Can kokushi stack with other yaku?
Generally no. Its unique shape excludes the normal sets-and-pair patterns, so it is scored on its own.